Monthly repeating bills get out of sync

[jonasbb]

I noticed that setting a bill as monthly repeating sometimes causes the bill to move by a couple of days forwards or backwards from the expected date.

Case 1

Case 2

When creating a monthly repeat starting on the first of a month I would expect all following entries to also have the first as the date. In case 1 it treats March as only having 28 days, thus creating two entries for March (1st and 29th) and making all following entries use the wrong day too (the 29th), resulting in a total of 13 entries for a year.

Case 2 shows an anomaly with December, where the months get cut short by a single day, compared to the three days of case 1. Case 1 didn't show any anomaly for December.

Here for testing I used the "Repeat now" button to expand a repeating bill, but I saw the same with the normal cron expansion too. The screenshot were taken from a system with Nextcloud Hub 3 (25.0.2), Cospend 1.5.5, PHP 8.1.13, MySQL 10.5.18. Please tell me if you need any more information.