Well I tried activating my virtual keyboard and couldn’t replicate this so don’t think that’s the problem. But you could at least confirm if it’s the same sound.
Right click on the transport panel (F2) and select virtual keyboard from the top area of that menu.
Now when you click on these virtual keys is it the same piano sound you hear?
If so all we need to do is work out how key actions are being converted to midi notes.
One thing…can you confirm it’s doing this in a brand new project?