Minecraft version

1.21.1

Describe the bug

If a mod (or datapack-as-mod) supports both Forge and Fabric, but does not support NeoForge, NeoForge will treat it as incompatible despite Sinytra being able to load it as a Fabric mod

Steps to reproduce

1. Install a mod which supports Forge and Fabric, but not NeoForge. For example, From the Fog's 1.21.1 mod form.
2. Put it in a NeoForge installation with Sinytra Connector and Forgified Fabric API.
3. Attempting to launch will show this warning screen:

4. Open the mod jar with a program like 7zip and manually delete `META_INF/mods.toml` (effectively making it just a Fabric mod). 5. The mod can now be launched with no warnings or errors.

Logs

https://mclo.gs/4QqYLPR (no crash occurs in isolation)

Additional context

In the case of From the Fog, it still seems to work perfectly if the user ignores the warning and proceeds to the main menu, possibly because the mod is actually just a datapack. Still, the warning suggests that it wouldn't work, and it seems like it can interfere with some other mods' loading, causing genuine errors elsewhere. As an example, BetterEnd fails to load at all if it's present when this error occurs (although that itself is a separate issue; this report is exclusively about NeoForge treating Fabric+Forge mods as incompatible).