misc you are the user nobody wants to support: you are mixing reports of whatever you are seeing on your setup with your conclusions. It is very hard to understand what the hell are you doing and seeing, at least for me.
Try to run tcpdump on that RPi4B and see what ping command is spitting out ( i guess tcpdump is available for arm, I never run a board with arm). Then move to laptop or other peer. It would be very nice to tell what did you installed on RPi, what other settings did you do, what type of connection you share (direct ethernet cable, switch, etc). Please paste the _original_ output, do not cut or modify it. Or ignore all this and forget about the debug and the answers ...
