Sometimes at the beginning of 2021, I started to have a problem with the "File upload" dialogs in the web browser. The dialog is unresponsive to the mouse. I can use the keyboard for navigation, but the Tab key only switches between the left panel and the "Search" field and I'm unable to focus the main area with files. Thus I'm unable to select a file, but I can escape that dialog with Esc and, as this regards also "Save as" dialogs, I'm able to select some directory in left panel's "Favorites" and confirm with Enter.
As time passes, I realized, that this problem applies to almost all native dialogs. I'm currently unable to open e.g. Pages or TextEdit, as it starts with the "File open" dialog, which I'm unable to handle.
And yesterday, I needed to tweak some configuration in "Security & Privacy" in "System Preferences" and I realized it has the same symptoms. I can click on the top navigation panel and return back to the "System Preferences" main screen, but I'm unable to click on anything in the "Security & Privacy" main section. The keyboard navigation works, but, again, the Tab key only switches between the left list and the "Search" field, and I'm unable to click on "Click the lock to make changes" so, it's all helpless.
I Googled for similar issues, but so far found nothing heplful.
Does anyone have some idea where to look, what to try?