How do I recover missing contacts on iPhone from iCloud?

Hi there,

Today my iPhone 16 pro suddenly shows only about 50% of my (mostly newer) contacts.

The older one are also missing in my favorites, my recent calls, my iCloud+ and Whats app.

Strangely the names in Signal are still present and these are my older contacts (family).

I already restarted my iPhone and I also went to my iCloud+ settings and tried to recover an older backup version of my contacts but both actions didn't help.

Does anyone have other suggestions?

[Re-Titled by Moderator]