Why does only one new user get's blocking Microsoft Defender message when trying to access Jira ?

[Matthew Doughty]

Hi Community,

I've created a new user for our instance but they receive this error message when they try to  access Jira:-

I suspect its not Jira but how do I get more information on Microsoft Defender, so that I can assist our help desk in resolving the problem ?

Thanks in advance,

matt