According to your testing, does the issue occur with ONLY Immersive Portals mod and Farbic API?

Yes

Describe the issue

Immersive portals is acting like it isn't downloaded when I have the fabric api and fabric itself

Post the log here

No response

?

it work weeks ago but now when i open it it dosent

Install mod menu to check whether you successfully installed the mod.

Does this mod show up in the mod menu?