Console does not see the subscription GPU

Adding someone to the "family" doesn't give them access to anything. The only way to share GPU is to have the account with the subscription sign in to whichever console you wish to share to. Then the account with GPU will make that console the Home console. That will allow all users on that console to use GPU. Just know that only one console can be set as an account's Home console.

Game Pass Ultimate merges with your current Xbox Live subscription.

So let's say you've got 3 months of Gold on your account and buy 1 month of GPU, you'll have GPU for the month and once that month ends you'll still have 3 months of Gold.

Game Pass Ultimate has Gold included itself, so yes it might have messed up your subscription.

I suggest going to the store on your console and head to the Xbox Live subscription area, see if they prompt you to buy it or see a date when your subscription ends.

nevermind, it works. I can see it spinning. But it does get extra hot around the vent. Is the fan sucking the hot air out? or is it just blowing on the gpu or whatever? If its blowing on the gpu, wouldnt that mess it up since its just blowing the hot air
throughout the console?

No, the display method does not matter. Geometry errors like you describe are an indication that the GPU is not processing data correctly. If it was stippled dots in the output, I'd say VRAM issue (that's my MW3 console's problem), but since you're seeing
geometry issues past experience has shown me that's a failing GPU.

Hi there,

If you add the Game Pass Ultimate (GPU) code, it will upgrade your subscription to that. If you have not had GPU in the past, the time left on your Live subscription will convert into GPU giving you a total of 9 months GPU. If you've had GPU before, then
the live time will convert at a lower rate.

More info can be found at the Game Pass Ultimate FAQ
here.

I've already had GPUs in the past, so now if I buy 3 months of GPU how many months will my subscription become in total?