Does failing to move the finger or deviating it from the Qiblah during the Tashahhud in prayer, then correcting it, invalidate the prayer?

What you are doing is a continuation of waswasa (whispering of Satan). Moving the finger during the tashahhud is a recommended sunnah, not an obligation. There is no need to repeat the tashahhud or any part of it if you did not move it. Some scholars even hold the view of not moving it, citing the hadith of Abdullah ibn Al-Zubayr as evidence. Your previous prayers, in which you repeated the tashahhud, are valid and not invalidated. If a worshiper intentionally repeats the final tashahhud and the salawat (blessings) upon the Messenger of Allah, peace and blessings be upon him, their prayer is not invalidated.