At a certain point a bias in the prng just has to become significant? This will be a function of the experiment. So I don’t think it’s possible to talk about a general lack of “practical impact” without specifying a particular experiment. Thinking abstractly - where an “experiment” is a deterministic function that takes the output of a prng and returns a result - an experiment that can be represented by a constant function will be immune to bias, while one which returns the nth bit of the random number will be susceptible to bias.