$$\biggr \lfloor \frac ab \biggr \rfloor^e $$
Or
$$\biggr (\biggr \lfloor \frac ab \biggr \rfloor \biggr )^e$$
I feel like the second option looks worse, but the first option assumes that a floor/ceiling function can "multitask" as a paranthetical enclosement. So, is the first one acceptable?
The first option is perfectly clear. Any function that encloses an expression would not need another pair of parentheses to enclose itself