I have a DHS N301 (National) I followed the advice in Zhang Jike's video and first sanded it, then wiped it with a damp cloth. After it dried, some of the wood grain began to stick out, so I sanded it again to make the surface smooth. After that, I applied a layer of DHS15 glue to remove wood dust. After that, I removed the glue, wiped the surface, and applied a layer of Donic varnish. Since then, I've re-glued the rubber several times without any problems. I'm sure the grain that started to stick out after wiping with a damp cloth would have come off during the re-gluing if I hadn't followed the above steps.
I varnish all my blades, but I agree that I haven't encountered this situation with any of my rackets from any brand. But the n301 plays superbly, so I believe that if you prepare the blade properly, it's top-notch.