I inadvertently figured out the problem. It turns out that there is nothing wrong with Zoom, but definitely some bugs in Samsung OneUI 6.1.
- The problem is that an Android/OneUI feature, called "Video Call Effects", seems to be getting turned on by default for some Galaxy users after the 6.1 update, forcing a background on some video calling apps (Zoom/WhatsApp/Meet) but not others (Slack Huddle). Refer to Samsung Galaxy forums, topic "UI 6.1 Video Call Effects NO Turn Off".
- What makes it worse is that apparently there should be a toggle button under Android Settings->Advanced Features>Video Call Effects, but this toggle is missing on my screen (also reported by others). Under this setting, I indeed see the salmon colored background selection that all zoom calls have, without any way to disable it.
- The solution is to turn off the Video Call Effect->background DURING A CALL.
- While in a video call (can be by yourself in a Zoom call), drag down the Android Status Bar (twice, to fully expand quick settings). At this point, a "Video Call Effects" option should show up at the top. Accessing this now allows the Background to be turned off.
- Once turned off, the setting persists across all other video call apps.
I hope this response helps someone else who comes across this problem, even though it technically has nothing to do with the Zoom Android app itself. Thanks to the Samsung community users who figured this out!
Including screenshots of problem and quick access setting to turn it off.