All requests that are sent to API of my instance back to me 500 error. They are correct

URL: https://jetbrains-league.monday.com/v2
Request example:

POST /v2 HTTP/1.1
Host: jetbrains-league.monday.com
Authorization: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Accept: application/json
Content-Type: application/json

{"query": "{ boards(){id name description state workspace {id name} board_kind}}"}