People crapping on this guy, except he’s reporting what is an actual known bug.
It’s related to the fix for the GoD exploit back in season 25. When you lagged the game out, you could get basically infinite momentum stacks and do basically infinite damage.
The fix for that basically means that under certain lag conditions, where you used to be able to get the exploit stuff going, you now just lose all your momentum stacks instead. You’ll have no momentum stacks and won’t be able to get more for a period of time until they get reset, e.g. after consuming a potion or changing floors.
It’s actually not him. It’s a known, but rare, bug.
He’s not the only one. Here’s a couple quick examples:
Jazz is correct, this is the reason for the bug. I’m guessing for OP it happened after grabbing the Bandit Shrine in an EN and the game lagged a bit from the goblins.