@GLAB Uno-Nrf comms are ok, your node woulnd't get to sending radio packest if radio chip comms weren't ok.
Instead of reflashing working node and gateway try backdating MySensors library in arduino. You should see what version is used in working gateway somewhere in your contrloller, or by connecing yor serial gateway directly to your PC. in case of ethernet/wifi gateway you can alco use MySController from here:
https://www.dropbox.com/scl/fi/prn9p2cnheyteopokszor/MYSController.zip?rlkey=up54kg4lt2blmff66t2jlgeo6&e=1
if your working node/gateway in on 2.00 and your new node works with that, then you can update them all with minimal risk of borking it all.