This is without a doubt AI.
There’s plenty of obvious AI mistakes on the character.
IF it’s official art, then the game uses AI art.

It's definitely official art, or at least the character is. Take a look at this stream from the game:
https://youtu.be/6IVuQsGHbP8?si=S6m-oZ-DyMs9l_Bj&t=2425

There are, however, a few differences such as the hair, so it's also possible this is a derivative work.

Also, it seems the developers acknowledged criticism of the game art's quality, but denied using AI:
https://www.reddit.com/r/gachagaming/comments/1ncelan/comment/ndwrg6b/

If it can be proven the developers are using AI in their official art, then it should be added to the game's wiki so uploaders will know to be careful.

Blank_User said in comment #2593014:

It's definitely official art, or at least the character is. Take a look at this stream from the game:
https://youtu.be/6IVuQsGHbP8?si=S6m-oZ-DyMs9l_Bj&t=2425

There are, however, a few differences such as the hair, so it's also possible this is a derivative work.

Also, it seems the developers acknowledged criticism of the game art's quality, but denied using AI:
https://www.reddit.com/r/gachagaming/comments/1ncelan/comment/ndwrg6b/

If it can be proven the developers are using AI in their official art, then it should be added to the game's wiki so uploaders will know to be careful.

I’d compare with post #10476998 (artist has done characters for Blue Archive), and the difference in the decorative details is noticeable.

This post seems to have the gold trim on the gloves because no doubt “gold trim” or something similar was in the prompt, there’s a few spots where it looks like the AI couldn’t decide if it should draw hair or not, and then the final star/cross ornament on the left side of the picture along the frill is just deformed.

Hard to prove it though.