You will have little to no meaningful autonomy, impact, or influence.
This is pretty much by definition true if the place you work at hits a certain size, you become an ant in an anthill, hyper-specialized with no meaningful holistic task.
Life is too short to move things in and out of protobufs for a living, I'd rather live in a garage like a broke college student and have some agency in a five person company and see an entire project through and do interesting work rather than fixing the pipes on some gigantic monolith.
I read that Airbnb blogpost recently about moving to react native and back and I can only imagine the amount of hours of human life that were wasted in meetings alone makes Kafka's novels look harmless, why do people do this to themselves.