I mostly use Google Photos, but I think there’s a bug. If you take a screenshot and tap on it while it’s still ‘floating,’ any edits (like cropping) aren’t saved, even after hitting save. However, if you tap one of the action buttons below the screenshot and edit from there, the changes do stick.
Interestingly, there’s no setting I know of to choose a default gallery app, and I’m not sure why it defaults to Google Photos. I’d be fine using Samsung’s Gallery app for quick edits, but tapping the screenshot defaults to Google Photos, which, as I mentioned, doesn’t work. If you open the screenshot manually in Google Photos, edits are saved properly.
Does this happen to you too?