@robertwgehl I know a little about this! I hate fullscreen apps so I go to great lengths to contain them, haha.

Possible solutions:
1. If someone screenshares, Zoom's default setting is to make your whole zoom window fullscreen.

If you don't want this, open your zoom app, click on your icon/profile in the top right, click Settings > Share Screen. At the top of this window you should see "Window size when screen sharing:" which has 3 options - Fullscreen, Maximize, and Maintain current size. The "Maintain current size" option will prevent your app from resizing itself when others screenshare.

2. I don't know if this setting is default, but in Settings > General there's a "Enter full screen automatically when starting/joining a meeting" option? You may want to make sure that's turned off.