Given this is a memory of her training with Batman, the assumption is that this panel takes place during the early days of Supergirl's time on Earth.
And Jamal Igle lets us know that by putting her in a costume more in line with the earlier issues of the book.
Notice how the shirt and skirt are a little bit smaller.
And can't you read her body language here? Bored/frustrated look on her face, hands on hips. It just speaks a bit more about the K-poisoned irritated angsty Kara seen in the first 19 issues of the title.
Contrast that costume to this panel which showcases some of the subtle changes Igle has made in the costume. Notice how the shirt covers a bit more of her ribs now, a strip of blue now evident under the S-shield.
And the skirt also rides higher and is little longer as well. We don't see the lines of Kara's pelvic bones anymore.
Lastly, I thought I would show the most controversial change Igle made, the inclusion of bike shorts under the longer skirt.
I did not put this post up to necessarily discuss the merits of the costume changes (although I like the changes Igle made).
Instead I posted it to show how the current creative team is doing the small things to put out the best product it can. The Batman panel shows that Sterling Gates and Igle care about details like costume continuity in flashback scenes.
And as I said way back when they took over in issue #34, I was glad that they weren't ignoring everything that had happened in the book prior but instead were recognizing and reacting to it. This was a 'soft reboot' with Kara's history (outside of her muddled 'Kill Kal-El' origin) kept intact.
As a reader I appreciate it when the writers and artists care enough about the character to get the small details right.