How to remove Null plot markers in QuantilePlot?

Bug introduced in 12.0 and persisting in 12.1.1

I want to change the plot markers of the data points in QuantilePlot. This seems pretty straightforward:

QuantilePlot[
                RandomVariate[NormalDistribution[0, 1], 32], NormalDistribution[mu, sigma],
                ReferenceLineStyle -> Directive[Red, Dashing[{Large}]], PlotMarkers -> {"[EmptyCircle]"}
            ] 

However we can see that we get a "Null" plot marker at either end of the reference line:

Is there a specific command required in QuantilePlot to customise the plot markers for the data points?

{mu, sigma} = {1, 2};

SeedRandom[1]

qp = QuantilePlot[RandomVariate[NormalDistribution[0, 1], 32], 
 NormalDistribution[mu, sigma], 
 ReferenceLineStyle -> Directive[Red, Dashing[{Large}]], 
 PlotMarkers -> {"○"}];

qp/. Inset[Style[Null,___],___] -> {}