The device gets hot or loses charge quickly while idle.
It sounds like you may have encountered a warning or a search result related to spyware in "MOD APK" files (modified Android app files). These modified versions of popular apps are a common source of malware and spyware. 1. How to Identify Spyware on Your Device You searched for SpyWare - Software & MOD APK Files
Background apps are uploading large amounts of data. The device gets hot or loses charge quickly while idle
Random restarts, apps crashing, or a noticeably slower phone. or a noticeably slower phone.