@RiotRepertoir Fizz ult is dropped by slow removing effects
In QSS change thread, You said that Fizz ult is CC, not bebuff. Link
And you did some work to Fizz ult.
Because of that, Fizz ult is dropped by any skill which removes slow effects.
Garen's Q, Evelynn's W, Master Yi ult... You can see the video here
Are those intendtional?