The cut is too high for the platform. I guess you take this number from Google/Apple store's commission.
The difference is software on Google's store has infinite leverage and takes almost 0 to scale sales. Every piece of art takes lots of work and cannot scale in the same way. Art works do not scale like software.
With this cut, I feel your platform is taking advantage of artists (they do not know where to sell) rather than helping them.
Even auction commission is only between 12 & 25%.