There is an issue with object masks. Results are coming back boxy and unusable. I have tried to use both smooth and sharp masking and both times its not clean. Further, I have also restarted the app + changed the resolution to Full + HQ playback.
Welcome to the Premiere forums, and glad you’re here. Thank you for including those screenshots of your masking issue.
We do need a few more details to try to help with the issue like computer specs, version/build of Premiere, if Windows what driver, etc. with our bug report details.