I learned that release action in GitFlow is merely merge develop branch(latest update) to release/XXX branch and put a TAG on it.

I would like to do simply as following:

git checkout -b release/XXX
git tag V1.0
git push

But when i try this on BITBUCKET, after i click start and finish New Release, i get additional operation on commit log as attached. green arrow: trigger release process in bitbucket , red arrow: another merge from main branch back to develop(which makes me confuse why it is needed)

enter image description here
enter image description here

Seems BITBUCKET do following things when i trying release with GIT-FLOW:
i would like to ask ：

1. why main branch is involved (step #3~#5) during release.
2. why an additional merge back to develop is need (step6) and what is the changes in main branch.

thank you in advance!

// on develop branch
git checkout -b release/V1.0  //#1
git tag V1.0                  //#2
git checkout main             //#3
git merge release/V1.0        //#4
git checkout develop          //#5
git merge main                //#6