How do I stop junk email from adding itself to my Calendar app?

Hello, for the last week I've been dealing with junk email that adds events to my Calendar app. Last night was the final straw, when a reminder woke me up at 4 AM.

I'm cleaning out the junk events the best that I can. I don't have any "rogue" calendar accounts that I can see. The only calendars I can delete are my close friends' birthdays and other major events. I'm not deleting that calendar. I will definitely delete the Mail and Calendar apps and switch to Outlook if this keeps happening though.

How can I STOP my Mail app from automatically adding junk mail invites to my Calendar app? As of now, I cannot find anything in Settings to stop this from happening. It's incredibly invasive. Any google searches I've seen on this topic go as far back as 2016, which is concerning.

Please and thank you for any assistance. I have already had this go off loudly AT WORK twice today.