@Riot Don't change Riven

She's healthy because she has plenty of counterplay, clear windows of vulnerability, obvious strengths and weaknesses, and has to interact with her laner to be relevant.

If the point is balance they should not touch her at all, she's very well balanced as she is.

I don't think Riven's kit is healthy and I don't think she's a well designed champion. I disagree. They gave her every single thing besides a heal basically No, no they did not. They gave her a gap closer, a shield, melee range CC, an AA modifier, and an execute. She has no point and clicks, no poke, no safe way to deal damage, no sustain, low base stats, sacrifices some of her damage to use her gap closer, cannot escape once she uses it, and is fairly easy to kite unless she flashes.

and she has almost no weaknesses as her kit negates them.

I'm not sure how, can you give me an example? Her weaknesses seem pretty clear to me. She's melee, squishy, extremely vulnerable during her Q CD, easy to itemize against, has locked MS with her dashes, which are interruptable, can be kited, has no sustain, relies on snowballing to impact the game, and falls off late game/during team fights.

Likewise she has clear strengths, high damage and mobility, very good in skirmishes, strong laning, good roams, etc. This is actually pretty ideal in terms of champion design.

hey made her a squishy melee champion, but she also has a shield that scales off her damage (she can build offensively for a stronger defense), and they also gave her a ranged execute with four low cooldown dashes that have AoE knockup/stun components to them.

Yes, she is a squishy melee champion, and all of those have some way in their kit to keep them alive during fights, otherwise melee champions wouldn't work. Master Yi has untargetability and meditate, Diana has an offensively scaling shield, Shaco has stealth and a clone, Renekton and Nasus have their ults and the ability to build fairly tanky, Irelia has CC reduction, Aatrox/WW/Xin Xhao/Irelia have heal on their autoes, Tryndamere can just straight up not die. Poppy negates the entire idea of a team fight, Fiora can parry almost anything in the game. Etc. Riven's shield is one of the least obnoxious melee defensive steroids in the game, and one of the more fair, on the level of someone like Fiora's; brief mitigation to damage which requires prediction or good timing to get the most of.

Almost every shield in the game scales with offensive stats, so that's normal. Her 4 dashes are more like hops, and together go only a bit further than your standard point and click gap closer, except that she can actually be kited, and if this happens she is in deep trouble, her MS during said dashes is locked at 450 which isn't actually a lot. The stun isn't actually tied to her dashes but yes she has melee ranged stun and knock ups, together they only last about 1.25 seconds if perfectly overlapped, however.

Riven needs more weaknesses that aren't so negated by her kit. Letting her get one kill can very easily mean the end of the game and there's not a whole lot you can do about it.

I disagreee here, as outlined above, and while yes she does snowball well it's pretty easy to stop her and "one kill" is a gross exaggeration. It's pretty simple to switch to a defensive playstyle, build armour, and keep wards down. It's less fun to build that way, but that is how you play from behind against any high damage champion.