Erm, while I agree Skype wasn't the pinnacle of chat software pre-MS acquisition, I believe OP is referring to their absolute butchering of the consumer client[0].

Anecdotally, I stopped using Skype for iOS shortly after it was changed because it went from a solid, reliable internet-calling service to probably the most buggy / laggy interface I could have expected.

[0] - https://www.zdnet.com/article/microsoft-updates-skype-after-...