Trouble receiving OTP on iPhone 15

Since I transferred my account from my iPhone 11 to my iPhone 15, I have not been receiving any OTP‘s. I have been in touch with Apple support said nothing to do with them. I’ve been in touch with my carrier who say they don’t block any codes, but it just seems coincidental as the day I changed to my new 15. I’ve not received one OTP anybody else got any problems like that