For some reason, I ended up on node2-test at one point, and AVG didn't like it.

node2-test was the temporary subdomain I pushed everyone onto to save them from having to wait for DNS to propagate when we moved servers.

Are you still getting this warning? Nothing really changed beyond the hardware & IP. Well, and SSL

Yeah, when attempting to replace www with node2-test, AVG still doesn't like it
If you mean if it throws error for www variant, then no. xD

On another note, when attempting to post with emoji, it gave fatal error

TEST 👽🛸🔥

Edit: Thanks for letting me know, it was a database issue... I switched us to MariaDB and the older MySQL version did some ridiculous things with encodings. It set the export columns to latin1 when it was quite clearly utf8.
Fixed it and it's tidied up the database quite substantially.

I've also reinstated the redirect to www. so anyone still on that temp subdomain should be fixed now.