When you run push, Git will refuse to complete the operation if the remote repository has changes that you are missing and that you are going to overwrite with your local copy of the repository. Normally, you need to perform pull to synchronize with the remote before you update it with your changes.

The --force push command disables this check and lets you overwrite the remote repository, thus erasing its history and causing data loss. Under the hood, when you choose to force push, IntelliJ IDEA performs the push --force-with-lease operation which is a safer option that helps you ensure you do not overwrite someone else's commits (refer to git push for more details on the push options).

A possible situation when you may still need to perform --force push is when you rebase a pushed branch and then want to push it to the remote server. In this case, when you try to push, Git will reject your changes because the remote ref is not an ancestor of the local ref. If you perform pull in this situation, you will end up with two copies of the branch which you then need to merge.