This is not a bug in ESP-IDF or Arduino-ESP32.
Because thisCharPntr is a static variable it's initialized to NULL. Evaluating strlen(NULL) involves dereferencing a NULL pointer, and dereferencing a NULL pointer is undefined behaviour in C. (strlen is a C function.)
Undefined behaviour means the implementation is allowed to do whatever it wants. Most computers (including ESP32) will crash. Possibly some implementations don't crash and will instead do something else.
C11 added a new function strlen_s() which has defined behaviour if the pointer is NULL (it returns 0).
Suggesting adding a null-check in your code if you need to verify that thisCharPntr is not-null before calling strlen(NULL)
You can read more about this here: https://stackoverflow.com/a/5796686/1006619