Vayne needs a hard nerf and then a rework?
I get it, people spam Vayne as she gives a lot of players an hyperinflated rank. If you are bronze/silver with ashe, your best bet to reach gold/plat is probably by starting to playing Vayne due to how much more forgiving and strong Vayne is.
The problem with Vayne is that she is more forgiving than most champs while also outscaling them hard. Vayne offers the players a lot more time to react to almost any situation than say an ashe would have.
Let's say Lux throws a skillshot against an Ashe, Ashe has to start moving INSTANTLY to dodge it. When you throw it against Vayne she can react sometimes half a second later due to how fast tumble is (almost like a mini flash). Vayne also has so many more escapes than others, an Ashe that overextends only have the ulti to get away (an ability you can flash/dodge). A Vayne can push you away (in a none dodgeble way, and get away), tumble away (not much you can do to stop that), go stealth (not much you can do to hurt a stealthed vayne) and so on.
Also Vayne out DPS you while the Ashe most likely don't, so it's more risky involved in ganking an Vayne, she can often win that 2v3, while Ashe better have flash up and react instantly the jungler appears on the minimap.
Vayne also don't have to worry so much about concepts like roaming. A Vayne just need to stay in her lane and get close to even in CS to win the game. Most other ADC's has the pressure to do stuff to help other lanes or game is lost. Vayne can just stay and farm while her team looses dragon after dragon and some towers, dragons/towers just don't matter much when Vayne hyperscale's so hard and will out scale everyone in just 5 more minutes.
Vayne while fun to play (as she is probably one of the best bet if you want to reach a higher rank) is not fun to play against, that's why she is banned so much.
An Ashe that goes 0/7 is almost guaranteed to be some sort of joke for the rest of the game, a 0/7 Vayne however have all sorts of comeback mechanics and can be 1-2 item behind and still often 1vs1 anyone and stay relevant as she split pushes. Vaynes main weakness is tumbling into the opponents team 1vs5 (while her flash is on cooldown), other than waiting for this to happen there isn't that much you can do vs a semi-fed Vayne.
Please give Vayne a hard nerf for now (community detest her as you can see on the ban numbers) and aim to rework her so she got some clear weakness, Vayne (and champs like her with almost zero perceived weakness) is bad for the game, as I believe not many is having a laugh facing her.