429 Client errorin Sharepoint with client_id, client_secret authentication

[Stefan2409]

I'm getting 429 errors on Sharepoint, even if the library just takes 2 requests to the sharepoint site.

I changed the authentication to app authentication with client_id and client_secret and gave all the needed permissions to the app.
Everything worked just fine before with user and password auth.

So my question is: what am I missing? Do I have to set some kind of rate limits for the app somewhere?

Thanks in advance for any help.