Today before maintenance, I had around 26 levels of XP (don't have a screenshot from today but I have one from yesterday with the same amount, pic related) but when I logged back on after maintenance the xp was gone. I didn't purchase any nstars with it, and I didn't enchant anything either. (this could probably be proven by looking at enchantment/nstar buy history) I'm not sure if this was because I was swimming in mining, but I don't think my player drowned while maintenance was going on as I logged on to the same place I was in before maintenance, with all of my things intact and a full breath meter.
A link to a folder with pictures showing timestamps, xp, and my xp level after maintenance:


Thanks for taking the time to look through this thread, I really appreciate it :)

 

Okay, I just checked this post and realized you can't see the pictures. Sorry about that.
Here they are:
https://i.postimg.cc/V66Rd5Vn/2019-07-30-16-59-40.png
https://i.postimg.cc/wB9FYw5W/2019-07-28-16-23-43.png
https://i.postimg.cc/P5s22XCn/2019-07-28-16-23-34.png