I tried again just now and it seems to be fixed, at least after 1 try. I kicked off 2 pretty large jobs in parallel and for the first time no errors with the authorization header.
HTTP 500 errors when including authorization header

I have sessions now and again when I receive a series of 500 errors for endpoint requests and I assume it's when the servers are under high demand and something has to give.
You wait a while and suddenly it's fine.

As 500 is an unspecified error, I suspect that your request never even got to the servers. I have seen instances where the C.C gatekeeper, Cloudflare, have sent that response.

True but I've started to notice that when an HTTP error is returned by Cloudflare, it's often in a separate range of errors reserved for that company. I had to look one unfamiliar error number up and it was describd as being an error generated specifically by a Cloudflare server.

I have sessions now and again when I receive a series of 500 errors for endpoint requests and I assume it's when the servers are under high demand and something has to give.
You wait a while and suddenly it's fine.
Make sense, but I would have thought in this case anyone with a session would have priority. Hopefully, it's not too common.
Has anyone else run into an issue where you get HTTP 500 errors at some point after sending back-to-back requests with an Authorization header? After some amount of requests, I just get constant errors. For example - I send 20 requests synchronously, and then the subsequent requests all return HTTP 500.
APIs work fine via my browser, so it must have something to do with my program. The only change I made was adding an authorization header with the token I obtained. I'm not sending requests in parallel and I have the user-agent header included. It seems to work fine if I don't include the authorization header. I'm following the example from the OAuth documentation: Authorization: Bearer {access_token}.
Being a 500 I'd assume it's not on my end. Is this a known issue or am I missing something?