Anniversaries calendar cannot be permanently deleted and reappears after removal

[garteful]

Checklist

• I can reproduce the bug with the latest version given here.
• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• I have taken the time to fill in all the required details. I understand that the bug report will be dismissed otherwise.
• This issue contains only one bug.
• I have read and understood the contribution guidelines.

Affected app version

1.10.3 (F-Droid)

Affected Android/Custom ROM version

Android 16

Affected device model

Samsung Galaxy A26 (non rooted)

How did you install the app?

F-Droid / IzzyOnDroid

Which calendar service or provider do you use, if any?

-NA-

Which sync adapter app do you use for calendar synchronization, if any?

-NA-

Steps to reproduce the bug

After accidentally selecting: "Add contact anniversaries" from the main menu, an "Anniversaries" calendar is created. When deleted via Manage Calendars, it reappears after a short time automatically, even though there are no contacts with anniversary data at all.

1. Tap the three-dot menu → "Add contact anniversaries"
2. Go to Manage Calendars → delete the Anniversaries calendar
3. Wait a few minutes
4. Anniversaries calendar reappears on its own

Expected behavior

Deleting a calendar from Manage Calendars should be permanent unless the user explicitly re-adds it.

Actual behavior

The calendar is recreated automatically, presumably by a background sync/refresh process.

Screenshots/Screen recordings

No response

Additional information

• Verified via ADB that the calendar does not exist in the Android Calendar Provider (content://com.android.calendar/calendars), it appears to be managed internally by Fossify.
• No contacts with anniversary fields exist on the device
• Device: Samsung / Android (non-rooted)

Thanks in advance!