I was about to install PixelFed, listed in Google Play as a 13-MB app, but it demanded to delete apps before I free 500 MB. Similar thing happens with F-Droid, although it gives less data. Why? Does it not, like Flatpak on PC, list dependencies? But that’s dumb; plus, no dependency for a browsing app may take 500 MB of space, and the demands aren’t getting smaller when more apps are on device.
From my experience filling my phone’s storage a bit too frequently, there’s a threshold where past that, Android considers as being low on storage, and starts doing contingency procedures to not fully fill out (if it does, data may start corrupting). Don’t know how short on storage you were, but from I observed on my phone at least, below ~1 GB, cached files start getting deleted, and below 500 MB, Android gives the persistent(ish) storage running out error. If you were on either of these thresholds, this may have been the reason.