Attributes don't work after death

Hello, I have found a rather interesting "bug". I am not sure if it is one, but max health attributes (using the /attribute command) will not exist after respawning in a single player world on 1.16.1. I was playing a superflat world with the starting configuration minecraft:air. Gamerules doDaylightCycle was false, keepInventory was true, and mobGriefing was false.