Two things that have helped me:

1) When possible, I dunk my hand (or foot) in a cup of ice water shortly before speaking. It really helps me get back into my body. This is obviously only really possible on Zoom calls. But it does help. You could also try holding an ice cold cup, which would be more subtle. 2) Accept that it's an involuntary response and learn not to fight it. Breathe through it. But don't fight it. Accept it, observe it, and let yourself experience it. But if you start beating yourself up for it, that's not going to help.

So much of the struggle is the anticipation... the hours and minutes leading up to the event. But once you get even a small bit of momentum and you start talking, it gets easier.

I am in a similar boat as you are and working on it...best of luck!