1. Reset Meet link: You can try resetting the Google Meet invite link if you have the permissions like the following user has done with success.

Success!! Go to settings on the google classroom and reset your meet link!
Source

2. Check if hardware acceleration is enabled: Google Meet's live background feature requires hardware acceleration to be enabled on your browser. To do this, head over to your browser settings and search up "hardware acceleration."

3. Clear browser data: If neither of the above worked, then you can also try resetting your browser. This can be done on Chrome through Settings > Privacy & security > Clear browsing data. A similar set of steps can be followed for other browsers too.

Users aren't just having trouble changing backgrounds though, as there are also plenty of other reports which state that the option to change backgrounds is missing altogether.

In this case, you need to make sure that your browser supports WebGL. To do this, head over to this link and check if the site looks just like in the screenshot below.

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