Google Chrome with taskbar entry but no actual window - how to fix

I recently got a new laptop - Lenovo X1 Yoga Gen 6 and thought that it's now-or-ever opportunity to head-dive into NixOS which was something I cherished for a long time. Anyhow, I have different DPI displays and hence need to run Wayland. Things are still a bit shaky with Wayland, at least on NixOS with KDE but it's getting better every week! - that's why I'm running on the unstable channel.

Every now and then after upgrade it happens that Chromium (and Chrome) open up but don't show a window. There is a taskbar entry, they respond to right-click, show recent docs in the right-click pop-up, etc., but not matter what I do, there is no window shown which makes unusable of course. This is how it looks:

How to fix it?

TL;DR;

cd ~/.config/chromium/Default
cat Preferences |jq 'del(.browser.window_placement, .browser.app_window_placement)' |sponge Preferences

How did I figure it out? I'm no Chrome dev so I did it a CLI way:

1. Copied my profile ~/.config/chromium aside, removed the original and checked that Chromium starts. I.e. it's a configuration issue
2. Used binary search to determine which files in the profile cause the issue - namely, each time I rsync -av ~/.config/chromium{.old,}/Default/, removed some files, and checked if it helped. Eventually I figured out that Preferences file is the offender
3. Now all was left is to compare the original and newly generated Preferences files. It's a single-line JSON file and I had to format it with jq tool first. Looking at the (huge) diff I was lucky to notice that .browser.window_placement configuration is different; and after copying Prefences from my original backup and dropping this attribute my Chromimum came back to life. Since I use Chromium web apps I had to reset .browser.app_window_placement as well

A bit of patience, a bit of luck and here we are! The same cure worked for Google Chrome. Hope this will help someone who stumbles on the similar matter. Of course if you have several Chrome/Chromium profiles you need to patch their Preferences too.

Update Jan 2022: Apparently the above hack works only partially and the issue kept triggering until Chromimum 97 landed in NixOS and it never happened since.