Chromium disappearing from task bar

I use Fedora 38, I have this problem since Fedora 37 if not 36.

Chromium browser windows, after some time, disappear from the task bar. I can still switch to them using Alt+Tab if they are under other windows.

Chrome works fine and I can’t work out the difference. Both use the “Classic” theme. Earlier Chromium used Qt and disappeared much quicker. It might be that Chromium disappears when it changes its icon, while Chrome never changes its icon at all.

How can I troubleshoot this?