Okay so I've found 2 things that are pretty annoying when dealing with the client-facing side of designing.
1. I typically only share prototype links with clients to give proper feedback. I don't like giving them back-end access to the files because they're usually messy, but I can if I prep a new file. So, I've noticed that when I comment on the design file from the backend version, yes it does show on the prototype side but the client receives an email saying I've tagged them in a comment with a link to said comment. When they click this link to go to the comment, they're redirected to gain access to the backend rather than the prototype side. This is extremely frustrating. I (and my team) should be back to comment from the backend with it feeding through to the prototype properly.
2. It would be amazing to be able to stop allowing comments on prototypes. When we have a creative that has been signed off, being able to stop allowing comments means that this is the final version and the client can't request any further changes. But it should be by Page, not the whole File because sometimes we work in batches, so we do need feedback on other working pages.
Oh this isn't client-related, but I'm also sick of breaking Styles to capitalise certain words rather than typing them in all caps (I don't want to preset the entire style to be all caps either). And also having to create multiple styles of the exact same font just because I need it in Regular and Bold.