Whenever I tap a button on any website that is supposed to start uploading process nothing happens. I don't get to see a file browser with which I am supposed to pick a file or anything else, only a slight website UI animation of the button responding to my tap if the website/button has one.

This has been the case from the moment I installed Firefox. It is the same in both regular and private browsing. I have looked at Firefox and Android app permission settings and haven't found anything and allowed everything relevant for Firefox to use (access to files, internet). I have no problem downloading files. I am using MIUI 13 Global.