I believe I'm a slow thinker too and it's always bothered me that in a work context there's an inherent advantage for fast thinkers due to the idea that the optimal way to solve problems is to "just jump on a call/huddle" or hash it out in a meeting. Coupled with the fact that many people never write anything down for asynchronous consumption it can be easy to become a bystander whilst decisions are made.

I feel the exact same. Quick calls and huddles give me anxiety. I can’t think of good ideas until I’ve had solo time to process the problem. Now I’ve resorted to sending my unsolicited ideas hours after one of these calls occurred and to my surprise they’re appreciated by the team so far. Setting a boundary and being vocal about needing heads down time to contribute most effectively could be worth trying.