Anniversary date not showing up in calendar

I have an iPhone 13 Pro running iOS 15.5, which is the latest version as of this post. I entered the anniversary date for a couple of my contacts and went to check the calendar to see if their anniversaries showed up . Although I see those contacts' birthdays I do not see their anniversaries on the relevant date in the calendar. This is a major bug and as far as I can tell there is no resolution. There was another thread on the discussions.apple.com going back to the year 2011 where another user complained about the same issue. I spoke to a few Apple Support reps on the phone but they were unable to help.

Very puzzled as to why this would not have been addressed by now.