Messanger contacts

I noticed that one of my friends no longer has a picture attached to their contact details. To me it seemed like the contact had been deleted. All messages sent from this contact are no longer visible but a blank bubble remains that shows there was originally messages which I can no longer see.

I noticed that another friend called me thru messanger had a social profile attached and was the colour red.

upon further investigation the friend that appears to be deleted had exactly the same social profile but the colour was blue.

can anyone help me know what’s going on and how I can rectify this?

(I'm not sure what topic I need to select below but it’s certainly something with Facebook & messanger apps)