If the number of reps has forcibly dropped to 3, that's a forced taper, no matter what label you give that day. If you do 5x3, that's a lot of volume on a forced taper, which will eventually lead to injury.
If the program is forcing you to make unexpected major changes like this, that's usually a good sign that the program isn't working as intended.
I don't think you can do an "Intensity Day" immediately after a "Volume Day" without making one of the two days ineffective.