I searched the wiki and expert takes thoroughly, but I couldn't find any mention of Brandon Aiyuk making a public appeal to the NFLPA for help. The wiki covers his situation in detail — the 49ers voided his guarantees, he needs to apply for reinstatement with the NFL Commissioner (not the NFLPA) before he can force a release, and he's considered "essentially untradeable" as of late June (from the Brandon Aiyuk page). But a specific appeal to the NFLPA isn't in the database.
That story may have broken outside the wiki's coverage window or from a source not yet ingested. If you have a link or more context, I'm happy to dig into what it might mean for his fantasy outlook.