The left shift key acts normally.
But if I press the Right Shift key and release it without pressing another key beforehand, Magic DosBox acts as though Shift is still being held. Lowercase lettters are typed as capital letters, “/“ is typed as “?”, “,” is typed as “<“, “1” is typed as “!” and so on. The Shift condition does not turn off until I either press Left Shift, or press Right Shift again and press another key before releasing it, upon which the Shift condition turns off.