Steam web api key error?

Question

Steam

When executing a request

https://api.steampowered.com/IDOTA2Guild_570/FindGuildByTag/v1/?key=<Мой_Ключ>&tag=628979

throws the following error

Forbidden
Access is denied. Retrying will not help. Please verify your
key=
parameter.

The key is correct, because when another query is executed with this key, everything works correctly.
What could be the problem or how to request guild data?