Vayne is even more of a problem with oracle lens nerf.

She was strong before, she's strong now, because unless you can kill her in less than 1 second like rengar or talon if he crits (Which is unlikely considering the youmuus crit removal.... if you're going to declare crit is not an assassin stat, then make their scaling not so god awful without it. Assassins can opt into essence reaver, but essentially all their items cost over 3k gold with the potential exception of last whisper variants and with how quickly games end, good luck with that.), then she's just going to go into stealth and the most you can do is use your oracle lens and follow her around aiming whatever skillshots you have at her while her team comes to kill you and she condemns you away when her stealth wears off before going into stealth again or flat out killing you.

Vayne wrongfully countered duellists/assassins that couldn't surprise one shot her before. Champions like Tryndamere, Yi, Shyvana, Aatrox, nocturne, etc should eat adcs like Vayne, but her condemn and insane mobility made it hard before, and now there is 0 chance of 1 v 1ing her unless you have room for a pink ward. She's literally Hanna Montana incarnate. She has the best of both worlds being the best tank killer and best duellist, and the only champions that can keep her in check are the buffed adcs that can potentially 1 shot her from the safety of range with burst from their spells which was not possible before unless significantly ahead.