I would like to add that using $CI_COMMIT_SHA (latest GIT commit) can be a good idea to track/detect a new application version. However, $CI_COMMIT_SHA is only reliable if every new/latest code change is a new commit that replaces the previous latest commit.

Developer might "reconstruct" a git branch history enough, that it will be effectively a new app version (based on actual code difference), but your pipeline or version detection logic will not detect that, because the latest commit SHA remained the same. Thus, your app may not notify the user of the change, for example, or some desired CI workflow won't happen because despite a change, CI_COMMIT_SHA has not changed. Or even if your app might still deploy with a new code version, not all deployment workflow steps will execute due to the latest commit SHA remaining the same.