The Open option for comments seem to always open using the internal browser but I have it set to the external browser.

When viewing a post with crossposts and changing the sort method, it's only applied to the top post and not the crossposts.

Saved comments don't have an overflow menu. And for me, I can't assign them to a folder because long-tapping on the comment, what I'd normally use to show the context menu, will load up the post for the comment.

Saved folders and its content can be deleted with a selection without confirmation. On a mobile app, I think a confirmation for this option would be useful as a mistap can delete a number of bookmarks.

I notice upvoted(probably down as well) comments don't seem to update the vote count until the app is reopened. So you could upvote a comment, come back hours later, see the comments and updated vote count on other comments but see the same vote count on the interacted one.

An error message comes up when viewing a Piefed inbox message. At least for read messages for post reply.