Is there a way of preventing the library Gx_EPD2 from displaying texts on the serial monitor?
Please post a link (using the chain links icon on the toolbar to make it clickable) to where you downloaded that library from. Or if you installed it using Library Manger (Sketch > Include Library > Manage Libraries in the Arduino IDE or Libraries > Library Manager in the Arduino Web Editor) then say so and state the full name of the library.
virtual void init(uint32_t serial_diag_bitrate = 0) = 0; // serial_diag_bitrate = 0 : disabled
@lesept, why do you clutter the whole forum with questions about GxEPD2? you know the topics intended for such questions.
Jean-Marc
Ok, I see the advantage of such temporary topics, they disappear in history! 
Thanks
I'll stick to the e-paper topic from now on.