There is indeed an rcParam that limits the maximum number of subplots per figure. It is set as an rcParam instead of a function argument in order to allow 1) having a shared default for all functions at the same time and 2) allowing to easily set the default depending on the computer capabilities.
ArviZ implements its own rcParams, based on matplotlib ones in order to make their usage familiar to matplotlib users, but they are not interchangeable. It can be modified with az.rcParams["plot.max_subplots"] = 200 or also with az.rc_context. Some plots also have a max_subplots argument.
I wrote a blogpost about ArviZ rcParams which could also be helpful.