I think they are missing an occasion with the ad tier here.
I would instead add this ad tier benefits directly to current gold service, rebrand it gamepass gold change it's pricing to 5$/months (current monthly equivalent to a year subs of gold, but reduce the delay to 1 month for the higher price (compared to the proposed 3$).
Then I'll also add gold benefits to current gamepass essentialy ending xbox live gold as a standalone service and providing multiplayer to every subscriber.
For current xbox live user that pay yearly. No chamge for them but they now enjoy a ad supported gamepass tier essentialy for free.
For those that pay monthly. I'll offer them the choice, same price same benefits + full gamepass or new low price same benefits + ad supported limited gamepass
I think this would streamline their offering.
If they still want a 3$ subs tier, call it gamepass silver. The exact same as gamepass gold but delay increased back to 6 month.