[Closed] drivetrain vibration?

sram rival + planet x xls

getting this strange vibration somewhere along the drivetrain, I think it's coming from the back, freehub or maybe even cassette/chain, and vibrating through the seatstays/chainstays

it's not there when coasting or properly gunning it, seems to only appear on the down stroke at cruise, when I'm just spinning fast enough for the freehub to pick up

used to just happen when the bike was in the stand, but now it's happening out on the road too, it doesn't seem to affect the performance of the bike but it's very ANNOYING

has anyone reading this experienced anything similar? dunno how to sort it as everything is done up tight and torqued correctly