Honestly, the nerf I want for Genji is just an HP reduction. Dropping to 175 or even 150 HP would put him in a state where I can deal with him as a support, assuming I can hit him.
The thing is, I would rather deal with Tracer than Genji, as Tracer dies to Kiriko/Zen HS + Punch combo, where Genji still needs another 50-ish damage after that, and if he’s close enough for me to punch, he’s close enough to basically OHK me with shuriken fan + dash. Add to that that Genji’s movement means getting that headshot in the first place is more difficult, and his ranged poke and ult are better, and you get the current situation. OW2, a Tracer with a heal orb generally can’t just do whatever they feel like in the backline, because if a support lands a skillshot on her, she either has to leave or is just dead. Genji can, because the extra 50 HP means he has enough buffer to get the kill anyway.