Is my phone being monitored?

I have had iPhone for years never had this issue before but the past couple days my phone has been acting really weird showing full service bars and WiFi but acting like there’s not… apps shutting down or acting weird, glitchy.. when I have it on speaker today it was echoing very obviously a few times .. things taking forever to load and my storage is constantly full and battery runs out so fast. Some settings have changed but when I notice it I also noticed I dontKnow how long it’s been changed for. I’ve gone through a lot of settings and from what I see there’s no funny activity going on as far as monitoring or forwarding calls but I also don’t know that much about it and I know things can be hidden. When I dialed the interrogation codes to see about forwarding it’s said SETTING ERASURE SUCCEEDED .. CALL FORWARDING ALL CALLS.. does that mean I disabled any potential forwarding?