That is strange, rening arenas are kept “fast”, that means not deep at all.
That is the way we keep ours, can’t slide in deep ground.
We also rope and do most all else, except cutting.
Cutting demands a deeper ground, so cattle don’t just take off and horses can hold the ends better.
You don’t need speed over distances in arena cutting.
One problem with working cowhorse, they need the deeper ground for the cutting part, the shallower one for the other.
Generally that is no problem as they have their cutting first for all, then groom the arena so it is not so deep, then do the rest, dry work and fence work in less “sticky” ground.
Maybe whoever kept that arena too deep didn’t know any better?