Glad to hear!

It’s likely because the in-app Tor connection is killed each time you put Zeus in the background. Apple restricts most 3rd party background processes outside of VPNs.

By running Orbot the “VPN” Tor connection remains active in the background and opening Zeus again doesn’t force it to reestablished the Tor again, just uses the active connection running in the background.

Also likely more stable than the built-in Tor library packaged in Zeus since all Orbot dev team does is try to get Tor to be stable as possible on iOS.