Shimano M6100 Brakes Free Movement in Lever?

Hey, got a pair of Shimano m6100 brakes which are around a year old but both levers have free flop in the end of them as seen in the video, both brakes work fine and they’ve just been bled.

I’m guessing this is an issue with a sticky piston in the lever or return spring as they shouldn’t be this floppy however I can’t see why they’re both like it at the same time at only around a year old?

Do I need to replace both levers? Any ideas? Thanks all!