Unusual battery drain
Phone overheating when not in use
Sudden spikes in data usage
Apps you did not install
Frequent crashes or freezing
Pop-ups appearing outside your browser
Unknown calls, texts, or emails sent from your phone
Settings changed without your action
Microphone, camera, or location activating unexpectedly
Strange account logins or password reset alerts
Security warnings from your device or accounts
Poor performance even after restarting
Phone behaving differently in safe mode
High background activity from unknown apps
SIM card or network issues you did not cause
Contacts receiving messages you did not send
New device logins on linked accounts
Browser homepage or search engine changed
Permissions granted to apps you do not recognize
Phone rooted, jailbroken, or otherwise modified without your knowledge