When the Push Check plugin has been enabled it's not possible to push without authorising the plugin to use JIRA.
The error displayed directly from git is:
[Syntax check] Permission problems. You are not allowed to execute the requested JIRA Rest action. Please ensure that authentication method OAuth is enabled. Also the OAuth options "Allow 2-Legged OAuth" and "Allow user impersonation through 2-Legged OAuth" should be set on both sides of the application link (in- and outgoing connections) (CredentialsRequiredException: You do not have an authorized access token for the remote resource.)
Did you face such problem, how can you force the plugin to authorize within JIRA per each individual user?