The transition that plays is always determined by the settings of the slide you are navigating to.

If you don’t want to use any 3D transitions on that last slide, please do the following:

• Select the target slide (the last slide)

• Go to the right sidebar → Slide → Timing & Transition

• Click the Select Transitions button

• Open the 3D category

• Remove the selected transitions by clicking on them

  or click Select All, then Deselect All

After this, no 3D slide transition will be used when navigating to that slide.