If you apply an Effect directly on a trimmed video on your timeline, the Effect preset still takes the duration of the whole media clip from your Media Pool (and not the trimmed version on your timeline). In order to get this right, you need to put your TL trimmed clip into a new Compound Clip, and then use the Effect preset on this Compound Clip, so that now it takes the duration from your timeline and not the Media Pool.

Here's a video tutorial explaining the above: