can I turn off time machine automatic backup?

Sure. Turn it it off in System Preferences > Time Machine. Make sure "Show Time Machine in menu bar" is checked then you can run a backup at your discretion.

Is there a particular issue being encountered with Time Machine here?

Time Machine picks up what’s been modified. All of it. It doesn’t pick up copies of everything else; of what else hasn’t been changed.

You could turn it off and restart it, certainly. But ponder whether you need the added cognitive load involved. Tracking what changed, what needs backups, what doesn’t, and just remembering to enable Time Machine after changes have been made.