GarageBand track volume jumping when I shift octaves on my controller

I have a Casio CTX-700 that I am using as a midi controller (NOT direct audio) for GarageBand. Since it is not a full range keyboard, I have set the first four presets to switch to different octaves, so preset 1 is normal range, preset 2 is -1 octave, preset 3 is -2 octaves, preset 4 is +1 octave. If it is unclear what I mean by presets, I have linked the manual for the keyboard. I am referring to the registration banks as presets. https://support.casio.com/storage/en/manual/pdf/EN/008/Web_CTX700-ES-1A_EN.pdf

Now, the problem: even when there is no track, and I am not recording, when I shift the octave, the volume of the track will jump up by around 1.8-2db. I have no idea why this happens, nor do I know how to fix it. This does not happen if I use any VST instrument as a standalone. I have attached a short video that shows exactly what happens. https://share.cleanshot.com/GLPCBRlp