[2021] Mastery levels (not weapon skill level)

There are many challenges for weapons and behemoths, so why is the maximum mastery level capped at soo low level?
I think for weapons it was lvl 20 and for behemoths and slayer lvl 50
Eg.: After you reach behemoth mastery lvl 50 you still have many unifnished challenges, but even if you finish them there is nothing to gain for it, aside from a check box in the challenge list.

Could you please make the cap higher?

I know it would mean, recalculating the level for the players, who already were at the cap, but I think it would be possible, taking into account that you still keep track of all the challenges after the player is at the cap.