Not possible to type in a birth date

Describe the bug

When I enter a date before 1.1.1970 for the birth date it is not accepted but changed to the current date.

Steps to reproduce

I hope my translations to English are correct:

1. Go to 'contacts' app
2. Click on 'new contact'
3. Fill in mandatory fields
4. Click on 'additional Information'
5. Select 'Birthday'
6. Enter a date before 1.1.1970
7. Save contact
8. Have a look at contacts field 'Birthday'

If you add a contact with a birthday before 1.1.1970 via Gnomes contacts app and sync, the contact is shown in Nextclouds 'contacts' app with the correct birthdate, but the birthday does not show up in the 'calendar' app.

Expected behavior

Birtdate before 1.1.1970 should be accepted

Actual behavior

Birtdate before 1.1.1970 is not accepted, but automatically changed to today

Contact version

8.3.6

Operating system

Firefox on bazzite

PHP engine version

None

Web server

None

Database

None

Additional info

My nextcloud instance is a managed instance by hetzner

Version: Nextcloud Hub 25 autumn

Start by reproducing the issue in the contacts app through New contact > Additional Information > Birthday, using a date before 1.1.1970, and compare the saved value with the displayed value. Check the related calendar-app behavior for birthdays synced from GNOME Contacts. Done means pre-1970 birthdays are saved and displayed correctly in Contacts and appear correctly in Calendar.