If you deal damage, or kill a player, or do anything else that triggers a temporary popup, its dismissal timer breaks and it remains on screen until the game restarts.
In the attached screenshot, I punched a player during the victory phase at the end of the round, and the damage popup remained...
GPU usage is oddly high in the buy menu.
Using an RTX 3060 on nixos-unstable, I was using proton-cachyos for these screenshots, but I get the same behavior on proton experimental.