AirPrint isn't working on Samsung Xpress SL-M2026W

AirPrint is a network-only solution, and will not work if the printer is concurrently connected via USB. Contrary to your experience, AirPrint should be functional with this device. Power off the networked SL-M2026W, then your Mac. Power on the printer and power on the Mac. Now, reset the print system again, choosing AirPrint as the driver. Is printing restored?

If you cannot get AirPrint working after the first paragraph, you may have to resort to a wired (USB) printer using the Feb 2021 Universal print & scan driver (v3.93.01) for macOS 11.3. Once downloaded and installed, reset the printing system using that driver instead of AirPrint. You should be able to print and scan using Apple's Image Capture.

With Big Sur, do not install any vendor software or drivers that predate 2021.

I would not expect HP to continue providing printer drivers for this Samsung device indefinitely and you should plan accordingly. The beauty of AirPrint is that (when it works) you are not dependent upon the device vendor for driver support. When macOS 11.4 is eventually released, I would advise you to attempt trying AirPrint again, in case Apple has silently updated it.

Any future printer consideration should be drawn from explicit, vendor-stated support for AirPrint, or from the long list of AirPrint supported devices.