[Ayesh]

Brotli support in API clients are quite low. I run a small API service, and you'd be lucky to see API clients even using gzip.

[synunlimited]

True, though given its relatively easy to support you could get some savings in the few cases that do use it.

Also if they own some/all of the SDK's that are used for hitting their API they could bake in brotli compression at that level.