Apple Calendar Subscription Requiring Username and Password

I noticed something a few days ago and my Apple Calendar was showing an ! next to my church calendars. I tried to update settings and found that the subscription now requires a username and password. My LDSTools account / web credentials did not work so I went ahead and updated my subscription URL under my calendars. This also prompted the same behavior. I tested on Google Calendar and although the subscription did not require credentials nothing is actually populating on the calendar. I contacted IT support and to the best of their knowledge there has not been a change to the authentication method or other announcements on this topic. I am curious if anyone else is having this issue or is this isolated to my account and additionally, if credentials are required if anyone knows the correct format. For instance for my company O365 accounts we have "friendly" email and usernames, but to login to microsoft there is a different format for username and domain.
Thanks for any suggestions on this!
side note: I did test iOS, OSX, google and android.

I'm able to duplicate it. You can test it just by putting the sync URL into your browser. You should be getting back an ICS file, but instead I'm getting a login prompt. But that browser is already logged into the calendar, that's how I got the sync URL.

Please note there is a 9 minute throttle - any requests within 9 minutes of the other will get a blank response.

I saw this issue for the last few days, but it appears to be resolved this morning (by no action of mine). Hopefully it doesn't pop up again.

HI All - I can confirm as well the issue has resolved itself and I am able to see calendar entries in Apple Calendar as well as Google Calendar. Thanks for everyone's replies - it was my first experience posting on these forums and it was a pleasant surprise at how fast responses were available.