Hi Josh, welcome to the forum!
Yet another occasion and need for improvement of GxEPD2...
GxEPD2 has an init() method instead of a begin() method like many other Arduino driver classes.
It would have an end() method if it had a begin(), but as I didn't like begin(), the end() is missing.
The next version of GxEPD2 will have an end() method, if I don't forget.
The end() method will call SPI.end() to release SPI pins, and reset all other control pins to INPUT.
For your Waveshare board with "clever" reset circuit, you would need this end() method.
In the meantime you need to implement this yourself.
PowerOff() or hibernate() don't switch off the level converter and RST transistor base resistor of the Waveshare board.
Of course you then need to call init(...) again to continue; init(...) with the shortened reset pulse.
Jean-Marc
In the Displays section of the forum, links to the devices are recommended (at least by me):
https://www.waveshare.com/product/displays/e-paper/epaper-3/1.02inch-e-paper-module.htm
https://www.waveshare.com/wiki/1.02inch_e-Paper_Module
https://www.waveshare.com/w/upload/4/4a/1.02inch_e-Paper_Module_SchDoc.pdf
Take a look at the schematics for the "clever" reset circuit, and its unreasonable low base resistor value!