>>51356875I just checked. she even giggles a little after saying Diantha is putting the pressure on. She's joking around, it's not the reason she's retiring. Notably this scene makes it seem like she just decided this, not that she came into the tournament with her mind made up or decided to shoot for world champ before retirement. It's a recent decision.
you can hear the giggle here too
https://youtu.be/ArgWbmDbicY?t=100She probably thinks she will breeze through the rest of the tournament. And probably expects it'll be unfulfilling. I personally expect we will hear some regrets about beating down very accomplished trainers that she has personally mentored. But if Ash puts up a good fight or beats her, I expect she'll change her mind. The "doubts of a mentor" thing would be a really interesting character arc so I expect some cheesy "reigniting my passion" stuff and don't have my hopes up for anything in great depth.