How do I fix iMessage sync issues between iPhone and MacBook Air?

My iphone messages do not sync with my Macbook air M1. I had this problem before but eventually it synced. It's been a few days now and it won't sync no matter what I try to do (restarting both the laptop and the phone, turning off and on the imessage setting). Every now and then it syncs the messages and then it stops again. I can't receive texts on the laptop. Only on my phone. If i send a message from my phone I can't see it on the laptop, if I send a message from the laptop I can see it on both the phone and the laptop but cannot see the answer on the laptop.

I don't know what I can do. I read some comments about "Text messages forwarding" but I haven't updated my phone to the latest version hence I don't have that option.

I would highly appreciate if someone could help me with that problem because it's not worth having this laptop if you cannot use once of its main features.

[Re-Titled by Moderator]