ihone is connected to MAC

Please try a different cable. or check the little contacts on your cable for corrosion.

if they are corroded you might want to clean up the corrosion to make it slightly more stable.

either way I would recommend getting a new cable.

What happens if you try connecting using Safe Mode?

Edit: It also indicates to me that the charging port on your iPhone may be the culprit.

That is usually a symptom which indicates a failing cable. Try a different cable, or a different USB port.