I did a quick search and found that there are dozens of discussions on Microsoft discussion forums and this Apple Community of other people experiencing the same thing. The common thread is various Microsoft-hosted accounts like Hotmail. Most solutions were folks report success involve using Outlook as the tool to resolve the issue. In Outlook, you can first make a setting to block future calendar spam, and then you can evidentially delete the events. One additional suggestion I found is that you should find and delete all traces of the email invites as well (from Trash, Spam, or whatever mailbox they ended up in). The following article has several links that detail how to delete the events and also stop it from reoccurring:
https://answers.microsoft.com/en-us/outlook_com/forum/all/how-to-delete-and-prevent-spam-invites-in-my/1394ff95-3e39-47ce-b86b-0d2f76d9e515
Because you may not have access to Microsoft Outlook on a computer, I recommend that you instead login to "Outlook.com" using your Hotmail user account. I recommend doing this from a desktop/laptop computer. From that web version or Outlook, try the following to prevent the issue:
- Log on to Outlook.com
- Click the Settings "cog" icon in the upper right
- You might need to then click on "View all Outlook settings" (may or may not be necessary for your account)
- Click "Calendar" on the left sidebar
- Click on “Events from email” (note that there also seems to be frequent reports of this screen being blank for some users)
- Turn the settings for each type of invite to “Don’t show event summaries in email or on my calendar”
Here is the official Microsoft support article about these settings -- scroll down to see how from Outlook.com web version (https://support.microsoft.com/en-us/office/automatically-add-events-from-your-email-to-your-calendar-32e5cf0c-3e65-4870-9ff9-df3683d3fc97). I hope that works for you because, I tried the same in my Microsoft 365 account and ran into another frequently reported Microsoft issue where the entire “Events from email” setting page is blank.