429 - Too many requests (end-user specific)

I know a lot resources are available for this particular issue, however, it seems to be affecting some users and not others, even when on the same network.

So:

Company A > (single) User A > “The Request Is Blocked” / Too Many Requests
> (single) User B (in same office) > No issue

It’s random, affects only certain individuals, within certain companies, cannot be reproduced.

We’ve got hundreds of clients on our Auth0 implementation with tens-of-thousands of users who don’t have this problem…

I should mention that the tenant logs show ‘successful login’, so this is after the token exchange?
(eg. as opposed to what is noted here: Rate Limits 429 errors )

What gives?