Is there a way to make the image gradually blur?

Just started using Shotcut so I am starting from scratch in many regards. Currently editing an interview video and between each question, I want to cut to B-roll with the question written out on it. I also want the image of the B-roll to gradually fade into a blur, so the text stands sharper. I can blur the image just fine, but can I time it so it isn’t blurred immediately, but instead gradual?

there is a old way, which requires more filters, but that will help you to do so.

The way:-

  1. Mask: Simple shape (Overwrite, preferred shape, keyframes if subject is moving)
  2. Blur box (at starting higher, and after time lower, keyframes)
  3. Mask: Apply

The Blur:Box filter can be keyframed. Apply it to the B-roll clip, and keyframe it so that the horizontal and vertical settings increase over time.

keyframes?

See here: Shotcut - Tutorial Videos