(Bug?) /oauth2/token for client_credentials returns UNIX timestamp

Yeah, my bad. It’s the https://id.twitch.tv/oauth2/token endpoint. My response looks like this:
{"access_token":"myaccesstoken","expires_in":5653581,"scope":["user_read"]}
However, my “expires_in” looks okay now, for some reason, but what about the refresh token? No refresh token for client_credentials tokens?