dash lights going dim then going bright

Have you checked alternator output? Load test it and bring RPMs up to driving speed to see if you have fluctuating output. Other thing is a bad connection or bad ground

It's the instrument panel circuit card, the surface mount components solder joints break or facture over the years during driving on the circuit card. If you can reflow the solder joints that are damage. Also the light switch control might be damage. All easy to change out or repair or replace. Go to youtube.

Had the dash board lights go dim then bright on a 2015 equniox , turned out to be a bad negative battery cable.