How can I uninstall one ui 3.0?

Hello, I’m new here, and this is my first post. I apologize in advance if this isn’t the correct category, nothing seemed to fit though.
I have a galaxy s10 plus. I just had a system update that installed one ui 3.0. It’s really messed up my phone. :pensive: EVERYTHING lags! The front face camera is suddenly very prevalent, it blocks my use of certain parts of apps, and evidently the bar that used to prevent that has been removed? :thinking: When trying to type the cursor sticks and when it unfreezes I get stuff like this (how to removu3g6e0.dsangly), which makes sending any msgs a long and tedious venture. Alerts pop up, but when I click on them, they disappear, and the volume control evidently decides for itself how loud it’s going to be! Those are just a few issues I’ve had in the 2 hrs since I updated… :sob:
Please please please tell me how to remove this update. :pray: