Hello.
Welcome to Frog Forum !!!
Yes, a constant 85% humidity is too high for Red Eyed tree frogs.
You could purchase a temp and humidity gauge w/ a probe?

See the Red Eye Tree frog care sheet here on FF for very valuable information.
(This includes all the information you need, including for temp and humidity ranges)

We could use some additional information:
1- what is the temp?
2- if using heat, what source ?
3. is the top screened. If so, is it covered ?

I use a little fan on a timer on extremely humid days in the summer ( Long Island , NY). However a fan is not typically needed.

Oh ! and by-the-way--- It is very smart to get things all set like this BEFORE you put the frog in