A very annoying bug: 180 duplicate of the same anniversary

Using /e/OS murenacloud
1

Today I noticed this very incredible bug: an anniversary repeated 180 times. I mean the same anniversary repeated the same day 180 times. A nightmare.
How can get rid of it?

EDIT
With Thunderbird I managed to get rid of it, selecting many occurrences at a time. But I think that developers should worry about a similar bug.

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2

After deleting that anniversary it was re-created over and over again: a nightmare.

3

Did you ever find a more permanent solution? Several of my contacts have 3 birthdays repeated on each occurrence.

4

No: and I don’t know if it is a Thunderbird problem or an /e/ problem: do you use Thunderbird?