This is actually 'expected behaviour', and arguably not a 'bug' ...
But it pretty much is a bug ... depends how you look at it
Attention to and compensation for frequency/phase response distortion as fc approaches sr/2 is one of the things that you pay for when you get an EQ that's been better designed.
ReaEQs peaking filters also have this issue. Btw, you want to be looking at the output spectrum with white/pink noise input (or plotting the output amplitude of a sine sweep over time), not just the GUI display curve; they aren't necessarily the same.
Fwiw, you'll see this with every (that I'm aware of) stock DAW EQ plug-in (perhaps except DAWs such as Sadie, Sequoia, soundBlade)