I found the solution on the Arduino site. Apparently the lastest version of esptool was not supported by the version the ESP32 core. I deleted the core and reinstalled it and now everything works again.

I found the fix on the Arduino forum:
See https://github.com/espressif/arduino-esp32/issues/7923
The workaround fixed the 1.8.19 IDE upload problem and the tools/ESP32 Sketch Data Upload problem both related to not finding esptool.
Arduino's IDE 2.0.4 does not support Sketch Data Upload so to do ...

MacOS 10.15.7, Arduino 1.8.19. Adafruit ESP32 Huzzah.
My IDE was working and then suddenly stopped uploading to the ESP32 board with error:
java.io.IOException: Cannot run program "___REMOVE___/esptool": error=2, No such file or directory
I changed to the Arduino IDE 2.0.4 and it works fine there ...