Just got the new a53 5g and noticed samsung have took the feature away blocked messages so I can't see any blocked contacts messages. I found this useful and this is one feature I did like about samsung
Hi, go into your messages, I'm using Google messages, at the top where the search icon is tap on the three dots & you will see the settings saying (spam and blocked)
Just wondering did you restore your new phone from your old device, if you didn't that may be the issue, you might have to add the blocked number again if you still have it.