I also updated to version 40 and I confirm what my TLE friend said, everything works well on Fedora 40, they have finally made Gnome's performance stable and it's about time I would say. I installed Chromium, I also found the favorites I had on version 87 which were obviously removed because there was no longer support as we all know. Except unfortunately I'm noticing that it has some bugs to fix unfortunately at the moment. I don't know if you too have had the opportunity to try Chromium but at least for me it crashes after a few minutes of use, at a certain point the browser freezes the hard disk starts loading who knows what and then Chromium closes at sudden. Fedora also detects an error on a component and obviously reports it automatically, so the first reports of malfunctions relating to Chromium on Fedora have already started. However, it's great that he's officially back on Fedora, that's what was needed too. Let's wait for them to start solving the first problems now.
