[10:05:52] [Render thread/ERROR] (ModNioResourcePack) Invalid path in mod resource-pack dynamic_fps: dynamic_fps:textures/battery/LICENSE, ignoring

This has no gameplay effect of course, but simply putting the file somewhere else would silence the warning.

I am using the Prism launcher that may set verbosity of logging higher.

MC 1.21, Fabric 0.15.11

I assume just renaming it to license or license.txt might fix that.
Could you tell me what Minecraft version and mod loader you use since this doesn't seem to happen on 1.21.0 with Fabric?

Awesome! I will include that in the next release then :)

Well I still can't get this to happen sadly. Could you try this build and see if it fixes it:

https://github.com/LostLuma/Dynamic-FPS/actions/runs/9854586279
Find the Artifacts section, download dynamic-fps-artifacts, open it, then the mod is in the fabric/build/libs folder.

The artifact looks like its not complaining