iOS 18 bug experienced by MANY on Reddit. Apple, please help.

Posting here so Apple is privy to the plethora of its customers experiencing this same bug and what they are saying on Reddit.

Issue (as it pertains to me):

-Since my father and I upgraded to iPhone 16 Pros, I am unable to initiate iMessages to him.

-In the new-message field, it shows Text Message-SMS; when I send him one, it fails.

-IF he first messages me from his phone, THEN the new-message field shows iMessage and for a period of time I am able to send him iMessages before it reverts to Text Message-SMS.

-Additionally, when I receive a message from my Dad, it appears on my Lock Screen as a group chat: It says "[his phone number] To you & [his name]"; e.g. "555-123-4567 To you & John Doe" (if John Doe were my father and that phone number was his phone number).

-This bug only impacts this single user - my Dad. This same odd nuance (only one contact being impacted) is reported by many others in the thread below.

Other background information:

-We are signed in to separate Apple IDs and did not have this issue in the past.

-We have verified we are only initiating iMessages from our phone numbers in Settings-->Messages-->Send & Receive.

-I have updated my phone to iOS 18.1 but the bug persists.

Here is the thread from Reddit:

One proposed test is to delete the chat thread and start a new one. At this point, I refuse to do this as my father is elderly and I refuse to lose 15 years of texts with him. That probably does not require further explanation.

Please, Apple - fix this!

[Edited by Moderator]