user-5ebe5

I can confirm this happenes in all 1.20+ versions. 
It's mainly annoying when you play on minigames servers where you die often and when you respawn you have to enable sprint again.

I've run into the same issue. The first player to hit an other player seems to get the killcredit (till the killcredit cooldown is over) and if a new player hits the same player it doesn't overwrite the previous hitter. This issue only occurs when you use you leftclick/hit a player. When you hit someone with an arrow or with tnt that carries your UUID it does overwrite it properly and gives the last hitter the killcredit.