It was only based on cata spawn size before the rewrite (over a year ago at this point), and so you could find a lvl 55 map on a lvl 10 finishing for example as long as the maze was created at lvl 35+. I wanted high lvl maps badly back then because they were barely dropping so I tried to get the word out and asked Alex to tell people for me too (I was too lazy to farm low lvl monsters for very long on a huge map since I wanted high lvl drops more than maps). In any case, I do not know if it still works that way since I remember one of the patch notes for the rewrite saying something about changing the way that maps are found, and also based on the number or high lvl maps that are being found recently compared to anytime in the past (maybe just an event effect though).
This shouldn’t be hard to test though. Someone enter cata solo during this event on a lvl 20 - 40, then get a friend to hold it and rejoin on a lvl 1 and blast the map down, reroll at lvl 10 and finish up the map like that. Make sure to reroll again right before you finish up and let’s see what you find ^ ^
( Can always get a tier 1-2 map even when you have a chance to find higher, so more testers would be good... I’m not gonna test it cuz that sounds like a terrible use of my time

)