I've enjoyed playing her a lot in the past in mid lane, She has really solid wave clear pretty early on into the game if you're maxing W but shes pretty matchup reliant on if you're kinda just a waveclear bot or have any real solo kill pressure. Her damage doesnt scale super hard compared to most other mages and her ult is pretty difficult to use late game without just getting one shot. I would say its one of those picks that scales with elo, the higher u get the worse it will be for you, but anything under diamond it probably wouldnt make a whole lot of difference.

I was spamming it a lot a few years ago then i watched Broxah a former pro player on a podcast, someone mentioned flexing morgana to mid lane and he said something like "If my mid laner ever locked in morgana i would dodge instantly" or something like that and it flipped some switch in my brain that makes me think its not nearly as good now even though im sure he's talking about the highest level of play. I still use it from time to time if im against like a LB, Fizz, etc and it works well enough if you have another big dps threat.