Why did cookies stop working when making requests in Steam?

Question

C++ / C#

Faced a limit on the number of requests on Steam, namely (429) Too many requests.
Yesterday I managed to get rid of this limitation (about 20 requests every 2-3 minutes) using cookies:

I add them to the request, everything worked fine:

But today the authorization failed. Perhaps due to the end of the browser session or their expiration.
The use of new cookies and many repeated re-authorizations in the incentive did not work.

Answer 1

The question is closed. There is no way around the restriction, cookies only gave the appearance of endless requests, since the request with cookies took 2-3 times longer.

Answer 2

Proxy to help

Answer 3

Did you manage to login to Steam?
Post the whole code please.