When I first joined a server, I was at level 151, I had 474,705 XP, and required 7000 Xp to progress a level [1st image]
I got server more levels, and eventually reached level 152. I completed a quest, and it took me down to level 134. (During this time, I had Twilight Bonus and the Seeding Bonus). [2nd image]
After more XP levels, I am at level 137, with 490,879 XP, with 750 XP required to progress. [3rd image]
Here is the pictures of it, the only truly important parts are the text boxes, but the rest of the image shows it happening across servers.
In addition, I am 90% sure I did not lose my chests that I gained from previous levels, and I do gain more chests from leveling up at this point.