Tiny brownish flat spot on gum where wisdom tooth used to be appear today, not sure what it is?

Neither am I. Needs to be seen to be diagnosed. Return to Dentist or Oral Surgeon who removed the wisdom tooth for evaluation. Probably innocuous.
Me neither. How long ago was the tooth removed? Although several possibilities come to mind such as slight depression causing shadow, pigmentation, amalgam tattoo are possibilities, it would need to be seen by a dentist to give you a definite answer.
Probably scar tissue. Scar tissue following wisdom tooth extraction is common, due to bleeding and adjacent tissue trauma. If it bleeds, exudes pus, or causes pain, see your dentist for evaluation.