Jenkins is getting build automatically twice likely because of GIT Scm polling - docker

Question

Problem Statement: Jenkins is getting an automatic build when only one build is pushed.
Project Setup: What I am trying to achieve is Jenkins-Github CI/CD setup. A simple Flask application is built and the same is pushed to Github test branch first. The repository has a webhook setup so that whenever a push event is detected a POST request to the Jenkins URL - this part is working fine. In Jenkins I have a simple Pipeline where I have the Github project configured and for Build option chose "GitHub hook trigger for GITScm polling". The pipeline setup is shown below. The pipeline (scripted) is also very simple -
builds a docker image of the flask application
performs few unit tests on the application
pushes the docker image to docker hub
pushes the code to master branch
sends notification.
What is happening that I observed: Once the github push is triggered and Jenkins build starts running which is expected but as soon as the 4th stage is reached observed that another Jenkins build is automatically started which I think is because of the webhook setup.
Now, I might be absolutely wrong as this is my first try (POC sort of) at Jenkins and also to be fair I was not very sure if I am doing/trying the right thing and also if this is the correct method to do such things. So, I would highly appreciate if I am being corrected here or atleast provided a correct approach. Please let me know if more information (script/code etc..) is required - thanks in advance.
Code used at scripted pipeline for pushing to master branch from test branch -
sh """git remote set-url origin git#github.com:xxxxxxxxxxxxxxx/FlaskApp.git
git checkout test
git pull
git checkout master
git pull origin master
git merge test
git status
git push origin master
"""
Edit:
Screen-grab of github webhook configuration-
Environment: Jenkins 2.249.1