iMessage randomly sending as SMS/RCS on new iPhone

I recently received a replacement phone after breaking my old one. I transferred over the SIM card instead of replacing it with a new one. My issue started a few days after this.

First, I would like to note that all messages I am talking about are to other iPhone users and no they are not the problem. It is definitely my phone.

When I send messages to individuals some are blue and working fine as iMessage and other individuals are sending as SMS or RCS. I am receiving all messages as iMessage but it’s completely random which people I am sending to as iMessage or text message.

On top of that, to some of my groupchats my messages are sending as green and creating duplicate groups. While other groupchats are working just fine as iMessages.

Lastly, all of my messages are showing up on my iPad as normal iMessages, but some are only sending to my iPad and not my iPhone.

I have tried completely resetting my phone to nothing. Rebooting, turning off iMessage, turning off SMS and RCS, signing out of iCloud on both devices.

I am at a complete loss.