Most verification/short codes not coming through since update

Ever since the update I haven't been able to receive 2FA/verification codes/short codes. I have contacted Spark and they said there's nothing wrong on their end. They ran through trouble shooting tips, reset the network at their end and my end, restarted and reset my phone, tried the airplane mode technique, reset message and network settings, checked who ive blocked, tried both on data and on wifi, everything. They said that it's not them. I spoke to multiple people too and they all said the same thing; that there's nothing wrong on their end, they can't fix it, and to contact the services I'm not receiving the codes from... That's not really possible these days with no one having customer service just help centres.

After trying with various websites I've noticed that the codes that DO come through are from companies in my country. Not a single code can get through from outside of the country. Even so, there are still a small number of companies in my country whose codes are not coming through. Thing is, all codes were working literally minutes before the update (2days ago) and since then I can't most of them. My mums just noticed that hers isn't working either (also a recently updated iPhone), but my sister still gets codes (same carrier, has a Samsung).

Could it be that the latest security update is so secure it's preventing messages coming in from outside the country? Unfortunately I have covid so no one will let me put my sim in their android phone to test my theory 😂 😭