If you want to nerf sona

Please nerf her hidden power that actually makes her dangerous

her q is not and has never been the problem. What makes her win games is her w and her e in teamfights. Her w in particular, has insane synergy with ardent censer, and outputs so much sustain from the shield alone. She is fun to play in lane because she does damage instead of being a boring healbot. Nerfing her q will maker her max w in lane and be an afk healbot, I can't believe that's what you want with her

I've won a lot of high elo games abusing this aspect of her, while going full damage builds on her is absolutely terrible against any competent players

I would actually increase the numbers on her w as well as its cooldown, to make its use a more meaningful effect but that requires more thinking of when is the optimal time to use it. Right now it's a spell you just cast off cooldown and apply shields/censer to your entire team for free every 4 seconds. In fact it's so powerful and spammable that you more or less need a tear to use it optimally or she goes oom in 10 seconds.

Her e also has insane bonuses lategame, and it lasting 7 seconds on sona instead of 3 is something that is entirely unneeded.

I feel like the nerf to her q mana cost and damage is going entirely in the wrong direction. It won't fix any of her lategame power (why she wins, and why she's broken in other game modes), but just make her laning phase weaker, and she's already weak there due to her heal being absolute garbage at low levels. She's a squishy immobile medium range poke champion which loses to any hard engage. Her problem is not her laning phase, and has never been. It's her lategame, due to the spammability of her w and e spells (in part thanks to the extra cdr on her ult) and items that multiply shields/ardent