So everything said in the blog post that's supposed to be new in build 18965 has already been available for me since build 18963. The Feedback hub updates and App restart after sign in feature, I received them in the previous Windows 10 Insider update.
Yes your PC has definitely sent logs diagnostics by now. you can still install that update though. there is a website that has links every official insider build that is on Microsoft servers. I used to use it to install insider builds that would give me error and wouldn't install through Windows update. (early 20H1 builds). but in the last 5-6 builds they were solid for me so I didn't need to download ISO file.
now that you're having the same problem 1. you can go here: https://uupdump.ml/known.php 2. choose the build you want and pay attention to the correct architecture (x86, x64, arm64). 3. click on it and then click next until you reach the download page page. 4. in there choose this "download using Aria2 and convert" 5. extract files on your computer and run the file. let it do its job and once its done it will give you a full ISO file that is officially downloaded from Microsoft servers.