@powersoft, @ajb2k3
Thank you both for your answers.
The board manager url found on https://docs.m5stack.com/#/en/arduino/arduino_development is apparently the old one and still does not contain the M5Paper board, but through the youtube video powersoft recommended I was able to find the correct url and everything works now as expected :)

Is there a working solution for the Arduino IDE as well?
Also: is there an official board configuration available yet? I only find M5Core, M5Stick C,... but none for the M5Paper

Is there a fix for arduino IDE as well? Having the exact same issue with the canvas size on latest arduino IDE. Or did I use the wrong board configuration? (Using M5Stack-Core-ESP32 because there is no dedicated M5Paper board config)