Guess Who the Popular Pop Star Is!!!

This successful pop star couldn't believe how big her third studio album blew up back in 2017 ... can you guess who she is?

We caught up with this star at LAX back in the day ... and congratulated her on all her success.

When asked if she ever thought she'd be back on top, this star told us she believed the clock has TikTok'd down on her time on top -- but, boy, was she wrong.