Same problem as reported (and fixed) here: #2201 Buffer is being allocated if `vsnprintf` reports 64 or more characters (due to the trailing \0): https://github.com/espressif/arduino-esp32/blob/310e78e6fded9414411eb48dcf212018c3791483/cores/esp32/esp32-hal-uart.c#L440-L441 But the buffer is only being released if *more than 64 characters* had been reported by `vsnprintf`: https://github.com/espressif/arduino-esp32/blob/310e78e6fded9414411eb48dcf212018c3791483/cores/esp32/esp32-hal-uart.c#L459-L460 Probably related: #2033 (happens only when debug is on and free heap drops by 64 bytes each time) Code to reproduce: ``` log_printf("1234567890123456789012345678901234567890123456789012345678901234"); ```