Yeah, normal keycap puller. Maybe I could have been more gentle I suppose, but everything points to it being an issue with the keycaps. Two broke during keypress, one during keycap removal, and one just happened to be broken when I next looked at the board.

It's not odd imo that they're broken on one side. Objects break at their weakest point first, that's just physics.

Honestly I'd love this to be my fault so that I can guarantee it never happens again, but it's hard to scientifically test how much difference it would make to more carefully add and remove keycaps when 94% are fine regardless and they feel and sound like the cheapest softest ABS there is.