@rpiloverbd, Hi, welcome to the forum!
Please read How to get the best out of this forum if you haven't done yet..
I try to understand which boards and panels you have. This would be much easier if you provide links to the devices you bought, or to the devices on the waveshare website.
Your picture looks horrible! It shows random content from the controller memory.
This tells me that SPI communication with the controller works, but data might have been transferred while the controller is BUSY. Check your BUSY line connection.
You could provide diagnostic output from GxEPD2, copy from Serial Monitor. Use a code window, please, </> command.
Your waveshare boards most likely have the "clever" reset circuit to switch off power completely. Use the init() method with shortened reset time, to allow proper reset of the e-paper controller.
Jean-Marc
Added: sorry, now I noticed the links you provided. But with shops on amazon or e-bay it is hard to match the displays to the corresponding panels from Good Display. Or they might even be from a different manufacturer.