@josh_bodner I've changed nothing outside of updating. I'm on the dev channel (obviously, but just to confirm), there was an update with a popup "Now you can sync extensions" (I think that was it). All my extensions are installed from the Chrome web store thingy, but after that notification I got 2 duplicated extensions installed from the Microsoft Store BitWarden and uBlock Origin, and a (semi-duplicated) Stylus Beta (I have the non-beta version installed) installed from the Chrome web store.
Other than that, nothing special.
I'm not particularly bothered about resetting everything to default or removing my profile altogether if it comes to that. Figured I'd wait and see if we have a bug I can help find first though. 
@josh_bodner Sorry for flaking out on the laggy browser when video is smoothly resized. At some point I grew tired of the browser crashing the GPU driver and went with the competition for a few weeks.
I have been regularly looking quickly at the weekly updates to see whether it got fixed, but it appears it didn't.
However I noticed today that it behaves differently depending on which display the browser window is residing. So it's possibly a multi-monitor related issue. Probably more so, because there's otherwise not enough people complaining about it (not that much people have more than one).
I have two displays here on a Geforce 2070S, both running at 1440p and 120hz. On the primary display, Edge becomes somewhat laggy while resizing video viewports and scrolling videos off and back on screen, while everything is relatively smooth on the secondary display (of course how smooth depends on the webpage and how complex it is). Not just a separate window, but moving the window that's problematic on the primary display over to the secondary display "fixes" it, until you put it back on the primary one, when it starts back up again.
If the issue starts happening (occasionally it's unproblematic for a short while after a reboot), you can already notice it when you play a Youtube video, then scroll so far down the comments that the video scrolls off display, you'll notice a short moment of laggyness during the transition. Same happens back on screen. If you do it often enough over a certain timespan (e.g. via regular browsing), the (NVidia) GPU driver gets upset and reinitializes, which manifests in the displays flashing black and then the DWM also reinitialising.
Sites with smoothly resizable video viewports are an easier tool to test, because it shows way worse there, but I'm currently hard-pressed to think of a video side doing smooth resizes that's safe for work. I'd tell you to move the vertical splitter between the video viewport and the chat area over on Chaturbate, but that'd probably doesn't fly at over at Microsoft at work. I suppose resizing the whole window forcing the video viewport to resize would exacerbate the issue, then it would probably work with Youtube et al.
Also, you asked me to look into edge://crashes, but there's nothing there, because the GPU driver crashes. Edge (and I suppose DWM) just reinitialises its graphics stuff during runtime and continue on merrily. This is what happens when Edge kills the GPU driver:
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--edit:
Re: this being a multi-monitor issue
I just disabled the secondary display, by doing into Display Settings -> Multiple Displays and drop it from Extend to Show Only 1, all during runtime, and suddenly Edge behaves well. As soon I go back to two displays by switching back to Extend, the browser window remaining on the primary display in the same position, starts acting up again.
--edit:
Ugh, I've updated Chrome and now it acts the same. So this crap is upstream. :|