When Quantization is on, all notes will be quantized to a note within the chosen key/scale. With Quantization off, you can still play notes that will be shifted outside of the chosen key/scale.
Example 1: In D Major, C# is part of the scale (the 7th degree or M7) and gives you a tritone because a perfect fifth of C# would be G#, and that is not in the D Major scale. If you play notes that are within the chosen key/scale, they will be harmonized to notes that are within the chosen key/scale. When you play notes that are not in the chosen key/scale, you’ll always get a perfect 5th, even if it is not in the scale.
Example 2: Same as above, you’re playing the 7th degree (M7) of the major scale. The perfect 5th would not be a note within D# major. Quant on/off will not affect this. The perfect 5th (A) would be the tritone of root note D# and would sound “dissonant”.
It sounds like in your other examples you are harmonizing with 3rds, and these harmonies are switching between major/minor thirds to fit with what notes are in the D Minor scale. When Quant is on and you play a D# (not in the D Minor scale) it quantizes this note to the next scale degree, which is the 2nd (E).
You can use other pitch-shifters that do not have key/scale parameters (Polyphony, Harmodulator) if always want a specific interval, for example, if you always want a fixed m3 harmony.
Let me know if that helps.
