I doubt this is a censorship, or a anti-counterfitting feature. It's most likely something wrong with the codec used to display images, possibly 10-bit heif photos are being interpreted as 8-bit jpegs. See other people getting the exact same shade of green in random photos:
There is nothing special about this shade of green that causes it to come from a codec issue. This green is what you get when you convert a 0-buffer from YUV to RGB. Depending on what colorspace you convert with it will be a slightly different shade.
You can play around with this yourself in imagemagick:
Conversion from YUV to RGB will be at one of the last steps of the image capture pipeline. Anything in between could wipe the buffer to 0s. It could be due to a simple bug in the image pipeline or it could be censorship. It tells you nothing.
Note that in the OPs photo (https://imgur.com/a/SCHGo4N) it happens to every other image consistently. If you were shooting raw (with Pixel, not familiar with Xiaomi camera), it would save the raw and jpeg together. The gallery not being able to display the raw image results in the green image would be consistent with whats being shown.
FWIW the redmi note 8 pro main 64mp camera (it's a Samsung sensor shared by many phones) can shoot in raw but only with a gcam port, not with the default Xiaomi camera app.
Making a guess here, the envelope has a distinct shade of pink, which may trigger some processing. It looks like it is in "AI" mode, and who knows what "AI" does.
You can play around with this yourself in imagemagick:
Conversion from YUV to RGB will be at one of the last steps of the image capture pipeline. Anything in between could wipe the buffer to 0s. It could be due to a simple bug in the image pipeline or it could be censorship. It tells you nothing.