In the following scenario the only way to reconnect to an endpoint is to swipe-kill the iOS app and restart it.
Basically I connect via Tailscale to my NAS. Then in order to connect to another VPN I have to stop tailscale (make it inactive) and I connect via PIA. After exiting my PIA connection if I re-enable the tailscale connection via the app, the connection does not come up and I cannot ping the endpoint. I have to kill and restart the app and then the connection works.
This is true even if I never make the connection inactive and just connect to a second VPN