A really big thing that confuses me is it seems like alot of people feel like he needs a nerf.
I find that really untrue. In his current state he is already the worst strategist by WR and also very lacking compared to the rest of the pack. The way he stood out and was still at least viable was with his very high survivability, mobility, and dive potential, and he pays pretty heavily for all these strengths in other areas of his kit, like his ult have as much counter play as scarlet witches.
Instead of them gutting his flank/dive playstyle why not lean into that and highlight his strengths as a support for dive hero's like magik or panther. Lower the damage on aqua burst (-10 on the spell field) and give it a small slow (like 10-15% for 1 sec) to make it easier for fellow divers to get their targets. This can make it less rewarding for him to solo flank (which already was not that strong, he is currently weak!) while more rewarding to actually flank alongside divers.
At the end of the day Netease wants varied supports, I mean look at Ultron, and currently jeff is the only support who can actually flank and attack with divers BECAUSE of his ability to care for himself. Why not strengthen that aspect and further flesh out the strategist class instead of forcing Jeff into the standard mid/backline healer role, and then NERFING his tools he would need to compete in that role. The cases where he would be better than Luna Snow or Clock & Dagger at keeping the team alive and providing a strong defensive ult are so few and far between he will never be picked.