I don’t know if it’s relevant to you, but one thing that caught me out was that changing the CPU clock speed after initialising the hardware serial port really messed things up.

(ESP32 WROOM 32) I'm struggling with running out of heap RAM on a program I'm developing. It needs BluetoothSerial and BLE, and WiFi is a 'nice to have' (for getting the time using NTP and retrieving logs). But, if I include all 3 libraries it keeps crashing or hanging because of lack of heap space....