iPhone Text message problem

After upgrading to iOS 18.0 my group and regular with SMS people l keep getting split up into different threads. Everybody in the threads have iPhones and android and before upgrading they were all working and sending/receiving iMessages just fine.

Now I'll have 2-3 threads with the same contacts (using their same phone numbers, not another contact point like iCloud email, Apple ID, etc.). My phone sometimes recognizes that the group is the same because it will automatically name the group the same thing, but other times it just puts the names of the people in the "To" line. In addition, some of the threads won't let me send iMessage so I have to reply in one thread and receive messages in the other (I send iMessages in thread A but the replies from the same people come back in thread B, but if I try and reply in thread B I can only send text messages even though all contact info is the same). And it’s also deleting conversations