My pushed code is not reflected in github's contribution graph.

Check if you are pushing your files to a branch other than main-branch, if yes then it will not reflect in your github's contribution graph, because github shows contributions only to the main branch of a repository, it's because of fact that you will be merging your other branches to the main branch at some point in time and don't worry when you merge your contributed branch to the main branch all the contributions made to that branch will start reflecting all of a sudden, it won't get lost.

for example, in my case, these many contribs started showing suddenly once I merged the branches.

How to merge 2 branches together in git?

https://hashnode.com/post/clecseyb700000aib3bf08unn