From the Federal Circuit Court of Appeals:

Opinion

And, contrary to UMN’s arguments, Saint Regis did not
base its reasoning on implied abrogation of tribal sovereign
immunity. Instead, Saint Regis concluded that IPR was an
agency reconsideration proceeding to which sovereign immunity does not apply in the first instance. 896 F.3d at 1329. This reasoning applies equally to states as it does to
tribes.

Article discussing the opinion here.