Tubi is one of the largest free ad-supported streaming platforms, offering thousands of movies and TV shows without a subscription. It's primarily available in the US, and a VPN lets you access the full Tubi library for free from anywhere. The reason for this is structural: streaming services license content country by country, and Tubi's catalogue in each market reflects whichever distribution deals were signed there. A title that's available on Tubi in the US might be on a competitor's platform in the UK, or vice versa.
A VPN sidesteps the geography problem entirely. Tubi sees the IP of GhostShield's exit server, not your real one, and serves you the catalogue for that exit region. The streaming app makes no distinction between a 'real' local user and a VPN-connected one as long as the traffic looks like residential broadband — which is exactly what WireGuard with ChaCha20-Poly1305 over GhostShield's network produces.
What you can't do is bend the laws of physics: a stream from Tubi's US servers will always have more latency from far away. Pick the GhostShield server closest to Tubi's data centres in the region you want, not the one closest to you.