Meta: frame blending
Frame blending is a type of interpolation where frames are combined by a transparent overlay in order to achieve a specified framerate. If you create a 24-frame animation with an intended duration of 1 second, and then export as a 30-fps video using tools like Sony Vegas or Adobe Premiere, enabling interpolation will generally result in six "fake" frames where one may pause and see two different frames blended through transparency.
Not all forms of interpolation are frame blending; some newer video editors use AI generation to create additional frames.
Frame blending is generally treated as a sign of low quality, as it's trivial to export a file that lacks interpolation.