Triggering of PR

Question

i have two branches

1)tech and tech-dev

one QA env other is dev env both have seprate yaml file for ci/cd

# Author: Anshuman Srivastava

trigger:

  branches:

    include:

      - techs-dev  # Only trigger on pushes to tsctechs-new

pr: none  # Disable ALL PR triggers

after adding this also
when i make a push any changes in dev env qa pipeline is also get triggered
infact when i raise a any other pr from xyz branch to abc branch all the pipelines (QA and Dev ) are get triggered
why is it so ?
how should i fix that?