Unusual battery drain
Phone overheating when not in use
Sudden spike in data usage
Random restarts or shutdowns
Apps you did not install
Strange pop-ups or ads
Background noise or echoes during calls
Delayed screen wake or lag
Text messages sent or received that you do not recognize
Changes to settings you did not make
Unknown devices logged into your accounts
Location sharing turned on without your consent
Camera or microphone indicator appearing unexpectedly
Security alerts from your phone or accounts
Increased app permissions you did not grant
Phone behaving differently after clicking a link or installing an app