Yes, I suggested running the reliable Dell Update or Support Assist - whichever is used for your model - in my earlier post yesterday. If it won't run I will help you fix or reinstall it as it is vital to get all of the latest drivers and BIOS and Dell makes it easier with this tool.
Did you do all of the other steps I gave for the Display adapter, and also Theme reset?
In addition try these fixes for Zoom flickering which is a known issue and will probably also solve the background problem:
https://www.dell.com/community/Inspiron/Camera-...
https://support.zoom.us/hc/en-us/articles/36006...
https://www.reddit.com/r/Zoom/comments/fyi2ip/b...
https://www.reddit.com/r/Zoom/comments/l661sz/z...
https://www.reddit.com/r/Zoom/comments/j5secj/s...
https://www.reddit.com/r/Dell/comments/gobnxi/s...
https://www.reddit.com/r/Zoom/comments/ikjzlr/s...
https://superuser.com/questions/1651550/zoom-wi...
https://www.youtube.com/watch?v=DE19a0pjHOE
Other fixes for desktop background randomly turns black:
https://windowsreport.com/desktop-wallpaper-bla...
(Avoid ad links which intrude into editorial copy, especially avoid Restoro, PC Repair Tool and Reimage ads)
https://winaero.com/fix-desktop-turns-black-in-...
https://forums.tomshardware.com/threads/random-...
https://forums.tomshardware.com/threads/desktop...
https://www.addictivetips.com/windows-tips/fix-...
Keep me posted on your progress as I will be here to help until the case is resolved.