I recently dismantled a Mavic Mini camera/gimbal and the outer lens glass (the rectangular piece) was accidentally and easily displaced, I imagine the
Mini 2's camera body is similar. If the glass is scratched and you wish to change it I would order one of the pattern? ones that seem readily available on the likes of ebay.
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Once you recieve it and verify it is not a piece of junk I would imagine that, with a pin or needle or scalpel, it would be fairly easy to 'dig' the original out of the camera body ( it comes off in the forward direction ) and replace it with the pattern one.
I assume they are glued in, I haven't checked, but I didn't notice any 'click' as it was displaced.