Daily calendar backup actually backs up calendars up to 120 times a day

### ⚠️ Before posting ⚠️

- [X] This is a **bug**, not a question or an enhancement.
- [X] I've [searched for similar issues](https://github.com/nextcloud/android/issues) and didn't find a duplicate.
- [X] I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
- [X] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/).

### Steps to reproduce

1. Enable "Calendar" under "Data to back up"
2. Enable "Daily backup"
3. See the results under the folder ".Calendar-Backup"

### Expected behaviour

A daily backup for each calendar.

### Actual behaviour

Each calendar is backed up multiple times a day, sometimes up to 120 (!) times within a single day. Contacts, however, are backed up only one time every day.

Examples:
```
Birthdays_2023-10-04_01-18-06.ics
Birthdays_2023-10-04_02-01-33.ics
Birthdays_2023-10-04_02-01-40.ics
Birthdays_2023-10-04_02-01-42.ics
Birthdays_2023-10-04_02-01-45.ics
Birthdays_2023-10-04_03-42-32.ics
Birthdays_2023-10-04_03-42-49.ics
Birthdays_2023-10-04_03-42-52.ics
Birthdays_2023-10-04_03-42-54.ics
Birthdays_2023-10-04_04-03-56.ics
Birthdays_2023-10-04_04-04-23.ics
Birthdays_2023-10-04_04-04-25.ics
Birthdays_2023-10-04_04-04-27.ics
Birthdays_2023-10-04_06-14-54.ics
Birthdays_2023-10-04_06-18-44.ics
Birthdays_2023-10-04_06-20-11.ics
Birthdays_2023-10-04_06-25-26.ics
Birthdays_2023-10-04_06-31-31.ics
Birthdays_2023-10-04_06-51-32.ics
```
and
```
Birthdays_2023-10-05_07-12-22.ics
Birthdays_2023-10-05_07-23-55.ics
Birthdays_2023-10-05_07-46-35.ics
Birthdays_2023-10-05_08-01-10.ics
Birthdays_2023-10-05_16-12-07.ics
Birthdays_2023-10-05_16-12-47.ics
Birthdays_2023-10-05_16-12-51.ics
Birthdays_2023-10-05_16-12-55.ics
Birthdays_2023-10-05_16-43-47.ics
Birthdays_2023-10-05_16-44-30.ics
Birthdays_2023-10-05_16-45-53.ics
Birthdays_2023-10-05_16-46-19.ics
Birthdays_2023-10-05_16-56-44.ics
Birthdays_2023-10-05_16-56-49.ics
Birthdays_2023-10-05_16-58-03.ics
Birthdays_2023-10-05_16-58-07.ics
Birthdays_2023-10-05_16-59-37.ics
Birthdays_2023-10-05_17-02-25.ics
Birthdays_2023-10-05_18-39-01.ics
Birthdays_2023-10-05_18-39-19.ics
Birthdays_2023-10-05_18-40-10.ics
Birthdays_2023-10-05_18-41-31.ics
Birthdays_2023-10-05_19-24-31.ics
Birthdays_2023-10-05_19-24-35.ics
Birthdays_2023-10-05_19-24-37.ics
Birthdays_2023-10-05_19-24-39.ics
Birthdays_2023-10-05_19-28-33.ics
Birthdays_2023-10-05_19-28-38.ics
Birthdays_2023-10-05_19-28-40.ics
Birthdays_2023-10-05_19-28-43.ics
Birthdays_2023-10-05_19-29-15.ics
Birthdays_2023-10-05_19-29-19.ics
Birthdays_2023-10-05_19-29-20.ics
Birthdays_2023-10-05_19-29-22.ics
Birthdays_2023-10-05_19-34-46.ics
Birthdays_2023-10-05_19-34-53.ics
Birthdays_2023-10-05_19-34-55.ics
Birthdays_2023-10-05_19-34-57.ics
Birthdays_2023-10-05_19-37-32.ics
Birthdays_2023-10-05_19-37-36.ics
Birthdays_2023-10-05_19-37-38.ics
Birthdays_2023-10-05_19-37-41.ics
Birthdays_2023-10-05_19-45-07.ics
Birthdays_2023-10-05_19-45-10.ics
Birthdays_2023-10-05_19-45-12.ics
Birthdays_2023-10-05_19-45-14.ics
Birthdays_2023-10-05_19-50-07.ics
Birthdays_2023-10-05_19-50-13.ics
Birthdays_2023-10-05_19-50-17.ics
Birthdays_2023-10-05_19-50-20.ics
Birthdays_2023-10-05_19-55-07.ics
Birthdays_2023-10-05_19-55-10.ics
Birthdays_2023-10-05_19-55-12.ics
Birthdays_2023-10-05_19-55-14.ics
Birthdays_2023-10-05_19-59-03.ics
Birthdays_2023-10-05_19-59-05.ics
Birthdays_2023-10-05_19-59-08.ics
Birthdays_2023-10-05_19-59-09.ics
Birthdays_2023-10-05_20-00-17.ics
Birthdays_2023-10-05_20-00-24.ics
Birthdays_2023-10-05_20-00-28.ics
Birthdays_2023-10-05_20-00-32.ics
Birthdays_2023-10-05_20-00-59.ics
Birthdays_2023-10-05_20-01-03.ics
Birthdays_2023-10-05_20-01-06.ics
Birthdays_2023-10-05_20-01-08.ics
Birthdays_2023-10-05_20-02-28.ics
Birthdays_2023-10-05_20-02-37.ics
Birthdays_2023-10-05_20-02-39.ics
Birthdays_2023-10-05_20-02-41.ics
Birthdays_2023-10-05_20-10-07.ics
Birthdays_2023-10-05_20-10-13.ics
Birthdays_2023-10-05_20-10-17.ics
Birthdays_2023-10-05_20-10-21.ics
Birthdays_2023-10-05_20-17-11.ics
Birthdays_2023-10-05_20-17-17.ics
Birthdays_2023-10-05_20-17-20.ics
Birthdays_2023-10-05_20-17-23.ics
Birthdays_2023-10-05_20-23-47.ics
Birthdays_2023-10-05_20-23-51.ics
Birthdays_2023-10-05_20-23-54.ics
Birthdays_2023-10-05_20-23-56.ics
Birthdays_2023-10-05_20-32-17.ics
Birthdays_2023-10-05_20-32-21.ics
Birthdays_2023-10-05_20-32-23.ics
Birthdays_2023-10-05_20-32-28.ics
Birthdays_2023-10-05_20-40-07.ics
Birthdays_2023-10-05_20-40-13.ics
Birthdays_2023-10-05_20-40-18.ics
Birthdays_2023-10-05_20-40-22.ics
Birthdays_2023-10-05_20-45-23.ics
Birthdays_2023-10-05_20-45-27.ics
Birthdays_2023-10-05_20-45-29.ics
Birthdays_2023-10-05_20-45-31.ics
Birthdays_2023-10-05_20-55-07.ics
Birthdays_2023-10-05_20-55-12.ics
Birthdays_2023-10-05_20-55-14.ics
Birthdays_2023-10-05_20-55-16.ics
Birthdays_2023-10-05_20-56-27.ics
Birthdays_2023-10-05_20-56-31.ics
Birthdays_2023-10-05_20-56-33.ics
Birthdays_2023-10-05_20-56-36.ics
Birthdays_2023-10-05_21-02-00.ics
Birthdays_2023-10-05_21-02-05.ics
Birthdays_2023-10-05_21-02-08.ics
Birthdays_2023-10-05_21-02-11.ics
Birthdays_2023-10-05_21-07-43.ics
Birthdays_2023-10-05_21-07-48.ics
Birthdays_2023-10-05_21-07-51.ics
Birthdays_2023-10-05_21-07-53.ics
Birthdays_2023-10-05_21-52-49.ics
Birthdays_2023-10-05_21-53-01.ics
Birthdays_2023-10-05_21-53-05.ics
Birthdays_2023-10-05_21-56-24.ics
Birthdays_2023-10-05_22-01-09.ics
Birthdays_2023-10-05_22-01-17.ics
Birthdays_2023-10-05_22-01-23.ics
Birthdays_2023-10-05_22-01-28.ics
Birthdays_2023-10-05_23-02-54.ics
Birthdays_2023-10-05_23-03-19.ics
Birthdays_2023-10-05_23-06-06.ics
Birthdays_2023-10-05_23-09-52.ics
```

### Android version

13

### Device brand and model

Samsung S20 FE

### Stock or custom OS?

Stock

### Nextcloud android app version

3.25.0

### Nextcloud server version

27.1.1

### Using a reverse proxy?

I don't know

### Android logs

_No response_

### Server error logs

_No response_

### Additional information

I will supply Android logs as soon as I can get my hands on the device in question.

I have no access to server error logs, but will ask the admins if this turns out to be necessary.