The Xbox App acts like i don't own gamepass ultimate pc subscription.

Hello WhyChiken,

Since you have Gamepass ultimate, that means you already have access to Xbox live gold, Gamepass for console and Gamepass for PC. To utilize the PC subscription, you just need to be signed into the same Microsoft account that owns the ultimate subscription.
Use the Xbox Beta app to get started.

For more information, check out the
Xbox Gamepass Ultimate FAQ

If you bought the Gamepass for PC and don't have an Xbox then getting Ultimate Gamepass is pointless. It would upgrade your subscription from Gamepass for PC to Ultimate Gamepass

No, They are not. I had GamePass PC earlier and everything used to work properly but then one day I got notification that there is an offer on GamePass Ultimate so I upgraded but since the day GamePass PC subscription ended and GamePass Ultimate subscription started, I can only launch games that are on EA Play and that too from EA Desktop App only.

Now, because the GamePass Ultimate was a 3 month subscription, so I can't even go back to GamePass PC until it's over.

Any game that launches from Xbox app for Windows fails to launch and tried repairing and resetting the Xbox and Microsoft Apps, sign-out and then again sign-in on both the apps but still same thing.

For Example, Forza Horizon 4 used to work earlier but now it does not.

The library of games for GamePass are different for Xbox and PC. If your subscription isnt' showing up in the Xbox beta app, try reinstalling it then signing in with the same account the Ultimate GamePass is on.

No, it's a gamepass ultimate subscription that I got from a store because it's cheaper than original gamepass subscription. It's between me and a pc user something like a mutual account