Are there any UX/UI public user feedback websites?

Go to UX/UI on Discord and visit #potfolio-critique. Mostly noobs, but some great designers post there from time to time.

You can try design communities on Slack as well.

https://www.designerslack.community/ (a list of Slack design communities)

https://designerhangout.co/request (invite needed)

https://thedesignership.com/ (public, 18k+ members)

I'm working on a little side project where you can share snippets of your design to test them for clarity (5-second tests, basically). The idea is you can go through everyone's designs, answer some questions about them, and then get feedback on yours.

Not sure if it'd be helpful for what you're looking for (and I'm just getting started so there aren't a lot of posts yet — working on that), but hey, worth a shot. IsThisClear.com