It's not recommended to run any of the Starr apps through a VPN. In some cases, it can cause connectivity issues such as the Starr apps not being able to update the posters and metadata, and sometimes the inability to add new movies/TV shows at all. It won't always happen immediately, but sooner or later it can and probably will happen.
!!! danger "To be clear it is not a matter if VPNs will cause issues with the Starr Apps, but when: image providers will block you and cloudflare is in front of most of Starr servers (updates, metadata, etc.) and liable to block you too"
Just run VPN on the apps that actually need it, like your torrent client, and perhaps in some cases certain indexers because of region/ISP restriction.
Please check the indexers rules if you're allowed to use a VPN/Proxy to access their site, being that VPN services often use shared IP it could be recognized as account sharing.
This isn't the same as the tracker, the API/Website scraping happens on the actual site and some indexers don't allow VPN usage on their site.