Minecraft version: 1.17.1
Forge version: 37.0.12*
Environment: Singleplayer

Mod name: Health Overlay
Mod version: from 1.17.1-3.0.0 to latest

Hi, I just want to inform you that your mod's data pack is outdated, so could you please update your mod's pack.mcmeta file?
It's out of date as of their pack formatting number since minecraft's vanilla data pack for 1.17 requires pack format of 7 not 6.

How I've managed to figure this out was when you create a new world and select the data pack menu selection screen, in there you can see all of your mod's resource pack aka it's data pack but it's red which means it's outdated and needs to be updated.

(*The devs of forge may have released new version(s) of forge for 1.17.1 already, so 37.0.12 maybe an older version of forge 1.17.1 now.)