iOS 17.3, deleting contact suddenly erased Whatsapp chat

Hey there, yesterday I delete from iPhone 15 Pro Max one contact.

after that I've noticed that our chat history completely deleted too.

I checked the WhatsApp Archive but it's not there.

I added that contact again but that not restored it or something, a fresh new chat completely.

I've tried it with another contact and the same has happened - deleting contact from my iPhone erased out chat too.

my friend did the same and it happened to him too.

In the past when I did it the chat history stayed with his phone number display instead of his name.

I did with an old iPhone 6S plus running iOS 16 (don't remember the exact 16) and it's not happening.

what is going on with that iOS 17???

help please!!!

thank you.