@AndrewAus
Could it be related to the new SmartScreen engine - which is the default engine since Edge version 103 if you have not configured the related browser policy setting "NewSmartScreenLibraryEnabled" to disabled?
Compare to
Microsoft Edge Browser Policy Documentation | Microsoft Docs
<...>
Allows the Microsoft Edge browser to load new SmartScreen library (libSmartScreenN) for any SmartScreen checks on site URLs or application downloads.
If you enable or don't configure this policy, Microsoft Edge will use the new SmartScreen library (libSmartScreenN).
If you disable this policy, Microsoft Edge will use the old SmartScreen library (libSmartScreen).
Before Microsoft Edge version 103, if you don't configure this policy, Microsoft Edge will use the old SmartScreen library (libSmartScreen).
The NewSmartScreenLibraryEnabled policy will allow enterprise customers to continue using the legacy version of the library until it’s deprecated in Microsoft Edge version 105.
<...>
Unfortunately we experience issues with the new SmartScreen engine on our Windows Server 2016 based systems, too, whereas the new engine is properly working on our Windows 10 based clients, which seems a little bit strange to me.
You can easily cross check by browsing the microsoft test page for SmartScreen:
https://demo.smartscreen.msft.net/
In our case, the old engine is properly working, the new engine unfortunately is not (checked by debug trace):
The old engine works without delays and properly blocks the dangerous actions (shows the desired behavior on the test page), the new engine does not, internally throws an error (no response) and just allows the action after the internal timeout:
OLD engine (SS_ERROR_TYPE_NONE, decision=kExploit):
{"args":{},"cat":"SmartScreen","id":"0x2f41dd80bc3778","name":"SendRequestProxy","ph":"b","pid":5712,"scope":"SmartScreen","tid":4192,"ts":93521246206},
{"args":{"server_uri":https://nav.smartscreen.microsoft.com/api/browser/edge/navigate/2/sync},"cat":"SmartScreen","id":"0x2f41dd80bc3778","name":"SendRequestProxy","ph":"n","pid":5712,"scope":"SmartScreen","tid":4192,"ts":93521246207},
{"args":{"request":"{\"config\":{\"device\":{\"appControl\":{\"level\":\"anywhere\"},\"appReputation\":{\"enforcedByPolicy\":false,\"level\":\"warn\"},\"pua\":null},\"user\":{\"uriReputation\":{\"enforcedByPolicy\":false,\"level\":\"warn\"}}},\"correlationId\":\"06931F68-AAF3-4E6F-8102-A319FC3C86AA\",\"destination\":{\"ip\":\"23.99.0.12\",\"uri\":\https://demo.smartscreen.msft.net/other/exploit.html\},\"forceServiceDetermination\":false,\"identity\":{\"caller\":{\"locale\":\"en-US\",\"name\":\"anaheim\",\"process\":null,\"version\":\"103.0.1264.49 (Official build) \"},\"client\":{\"data\":{\"customSettings\":\"F95BA787499AB4FA9EFFF472CE383A14\",\"customSynchronousLookupUris\":\"0\",\"edgeSettings\":\"2.0-2f9188b68640dbf72295f9083a21d674a314721ef06f82db281cbcb052ff8ec1\",\"synchronousLookupUris\":\"637928652443953878\",\"topTraffic\":\"637811103879324684\"},\"version\":\"281479416053761\"},\"device\":{\"architecture\":9,\"browser\":{\"internetExplorer\":\"9.11.14393.0\"},\"cloudSku\":false,\"customId\":null,\"enterprise\":null,\"family\":9,\"id\":null,\"locale\":\"en-US\",\"netJoinStatus\":3,\"onlineIdTicket\":\"t=GwAWAd9tBAAUa9NnKxE2EcNyf3boVjyC/9kKG5YOZgAAELAeEOMJS3E3tCal2CDDdQPgAAjdYXHl+RDzDkifveluYGXfVUwUY+hASt1HKHZEiiRCxJvSAthVIlm44A7NYRCpepRnfk4ExYyHzlkI937HAesH2EMohRgGHiVZElouy9UT3qiotJBGNlUhKR9ebkD1anWNxhRs7vJCGLcTpgsW7mRRzCRRzHFryF9HICZSMH4t04BqCFhcwJ5iGu2Knh5nSCxISUvvpp+BLkZ7arHFsub8/M8EZGluZqWRy24Zig2Fr5lRr0uLYRIoPprM81N8yhavbcsqmkx/MAhnHdvf+YCRKfg7GLKN4SIZBLZrlnLIIAE=&p=\",\"osVersion\":\"10.0.14393.5192.rs1_release\"},\"user\":{\"locale\":\"en-US\"}},\"referrer\":{\"ip\":\"23.99.0.12\",\"uri\":\https://demo.smartscreen.msft.net/\},\"serverContext\":null,\"signals\":null,\"synchronous\":true,\"systemSettings\":{\"battery\":null,\"network\":null},\"type\":\"top\",\"userAgent\":\"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.5060.114 Safari/537.36 Edg/103.0.1264.49\"}"},"cat":"SmartScreen","id":"0x2f41dd80bc3778","name":"SendRequestProxy","ph":"n","pid":5712,"scope":"SmartScreen","tid":4192,"ts":93521246360},
{"args":{"response":"<Res>\r\n <S>0</S>\r\n <I>06931F68-AAF3-4E6F-8102-A319FC3C86AA</I>\r\n <W>637928616292506341</W>\r\n <R>\r\n <Rs>\r\n <M>ZGVtby5zbWFydHNjcmVlbi5tc2Z0Lm5ldC9vdGhlci9leHBsb2l0Lmh0bWw=</M>\r\n <C>XPLT:100:0:0</C>\r\n <T>7200</T>\r\n <L1>9db8fb1a</L1>\r\n <X>0</X>\r\n </Rs>\r\n </R>\r\n</Res>"},"cat":"SmartScreen","id":"0x2f41dd80bc3657","name":"SendRequestProxy","ph":"n","pid":5712,"scope":"SmartScreen","tid":4192,"ts":93521446375},
{"args":{},"cat":"SmartScreen","id":"0x2f41dd80bc3657","name":"SendRequestProxy","ph":"e","pid":5712,"scope":"SmartScreen","tid":4192,"ts":93521446379},
{"args":{"response":"{\"actions\":[{\"$type\":\"cache\",\"key\":{\"uri\":\"demo.smartscreen.msft.net/other/exploit.html\",\"inheritance\":\"none\"},\"maxAge\":100800000000,\"serverContext\":\"1;f94c025f-7523-6972-b613-ce2c246c55ce;UNKN:100;0.01\",\"responseCategory\":\"Allowed\",\"result\":{\"$type\":\"evaluate\"}}],\"serverContext\":\"1;f94c025f-7523-6972-b613-ce2c246c55ce;UNKN:100;0.01\",\"result\":{\"$type\":\"evaluate\",\"responseCategory\":\"Allowed\",\"serverContext\":\"1;f94c025f-7523-6972-b613-ce2c246c55ce;UNKN:100;0.01\",\"feedbackUrl\":\https://feedback.smartscreen.microsoft.com/feedback.aspx?v=6&t=12553&result=none&type=top&ur=UNKN%3A...}}"},"cat":"SmartScreen","id":"0x2f41dd80bc3778","name":"SendRequestProxy","ph":"n","pid":5712,"scope":"SmartScreen","tid":4192,"ts":93521446591},
{"args":{},"cat":"SmartScreen","id":"0x2f41dd80bc3778","name":"SendRequestProxy","ph":"e","pid":5712,"scope":"SmartScreen","tid":4192,"ts":93521446594},
{"args":{"result_decision":"decision=kExploit, \nurl:https://demo.smartscreen.msft.net/other/exploit.html","step":"OnComplete"},"cat":"SmartScreen","id":"0x2f41dd80bc2575","name":"CheckUrlsForNavigation","ph":"T","pid":5712,"scope":"CheckUrlsForNavigation","tid":4192,"ts":93521446607},
{"args":{"error":"SS_ERROR_TYPE_NONE","step":"SmartScreenError"},"cat":"SmartScreen","id":"0x2f41dd80bc2575","name":"CheckUrlsForNavigation","ph":"T","pid":5712,"scope":"CheckUrlsForNavigation","tid":4192,"ts":93521446612},
NEW engine: (SS_ERROR_TYPE_CLIENT_CRITICAL, decision=kAllow ?!)
{"args":{},"cat":"SmartScreen","id":"0x2f41dd8e282986","name":"SendRequestProxy","ph":"b","pid":576,"scope":"SmartScreen","tid":5024,"ts":93746423411},
{"args":{"server_uri":https://nav.smartscreen.microsoft.com/api/browser/edge/ssrs/3?MSURS-Client-Key=+c8/QC27iQm6lpyb8mwlo...},"cat":"SmartScreen","id":"0x2f41dd8e282986","name":"SendRequestProxy","ph":"n","pid":576,"scope":"SmartScreen","tid":5024,"ts":93746423413},
{"args":{"request":"<Rep v=\"3\"><G>{379BDC39-D58D-44AA-986B-FD2CBFFA75A6}</G><ORG></ORG><SEN></SEN><ID>{3577E9B1-CCA1-4CA3-8C69-B6C27D3B289C}</ID><C>Anaheim</C><OS>10.0.18363.720</OS><L>en-US</L><W>0</W><I>{381ddd1e-e600-42de-94ed-8c34bf73f16d}</I><R><Rq><U>aHR0cHM6Ly9kZW1vLnNtYXJ0c2NyZWVuLm1zZnQubmV0L290aGVyL2V4cGxvaXQuaHRtbA==</U><T>T</T></Rq></R></Rep>"},"cat":"SmartScreen","id":"0x2f41dd8e282986","name":"SendRequestProxy","ph":"n","pid":576,"scope":"SmartScreen","tid":5024,"ts":93746423438},
{"args":{"response":"NO RESPONSE"},"cat":"SmartScreen","id":"0x2f41dd8d478200","name":"SendRequestProxy","ph":"n","pid":576,"scope":"SmartScreen","tid":5024,"ts":93752716811},
{"args":{"result_decision":"decision=kAllow, \nurl:https://ntp.msn.com/edge/ntp?locale=en-US&title=New%20tab&dsp=1&sp=Bing&prerender=1","step":"OnComplete"},"cat":"SmartScreen","id":"0x2f41dd8d477a47","name":"CheckUrlsForNavigation","ph":"T","pid":576,"scope":"CheckUrlsForNavigation","tid":5024,"ts":93752716902},
{"args":{"error":"SS_ERROR_TYPE_CLIENT_CRITICAL","step":"SmartScreenError"},"cat":"SmartScreen","id":"0x2f41dd8d477a47","name":"CheckUrlsForNavigation","ph":"T","pid":576,"scope":"CheckUrlsForNavigation","tid":5024,"ts":93752716910},
