I just got my A71 5G about 4 days ago. I'm most familiar with Samsung products but my last phone was an S7 from 2016.
After scavenging through YouTube tutorials and other forums, I've seen this as a problem for other phones, but with no real solution other than the lead that it was fixed with an update.
Overall, I know I can receive group texts--(but not one I needed to respond to). My problem lies in trying to create a group message and it was sent individually to each person. Which caused confusion. I've gone through settings. The only thing that seems applicable, that is already turned on anyway is "Group Conversations- send text and multimedia messages to multiple recipients as group conversations so that everyone can see all the responses."
If it's important, my carrier is Verizon and that is where I got the phone from.