According to Cheat Sheet, there's a real possibility that Miley still has Liam's last name. The article quotes a February 2019 interview that Hemsworth did with Live with Kelly and Ryan where he talks about his new wife taking his name.
The actor told the hosts at the time, "Miley Ray Hemsworth now, actually. She will still be obviously known as Miley Cyrus, but she took my name, which is great. I think that was honestly one of the best things about it. I didn’t ask her to take my name, but she was like, 'No, of course, I’m taking your name.'"
Although that's not exactly surprising, it looks like Miley hasn't changed her name back to Cyrus--at least not yet.
The article explains, "Of course, it’s possible that Cyrus could’ve changed her name back to Miley Ray Cyrus following her divorce but, so far, no reports have shown that."
However, it looks like their name might be the only thing tying the former couple together.
Miley has been happily dating new beau Cody Simpson for months, and it seems like their relationship is only getting stronger.
For his part, Liam is now dating model Gabriella Brooks though they have kept the details of their relationship pretty quiet--especially in comparison to Cyrus' PDA-filled posts with Simpson.
It also could be a matter of a busy schedule keeping Cyrus from making her name change official. The star has been staying busy throughout quarantine by working on her "Bright Minded" talk show and (possibly) new music!