UI laggy after switching back to game process

Playing on android phone (Samsung S22 Ultra). When I have to switch to another app, then I switch back, the UI is a bit laggy, resulting in stuttered screen updates and slow response to screen presses. Graphics are all the way up, 30fps limiter enabled, as I’m on a good phone, and normally, it runs fine and smooth. Toggling the limiter and 3D backdrop buttons has no effect. Lowering graphics level returns to smooth operation, but returning to high level reintroduced the lag. Only FC then relaunch gets rid of the lag.