I've adjusted derailers on just a few bikes. So out of comfort zone giving advice here.
Previous poster questioned if you checked if derailier is in alignment? That would be good to know. For smooth chain travel.

I bought a used bike last year, that had a visibly bent derailier hanger. Instead of taking to a bike shop. I bought a "derailier hanger alignment gauge." lt mounts where rear derailier is threaded into hanger. Then it's arm is rotated to top, bottom, left and right 90°positions on wheel rim. Using the adjustable chrome bar, compare dimension to rim at each 90°position. And the gauge is used to bend hanger close to alignment. Think I paid around $30 US for an off brand. I don't know if that could be part of the issues? Or, would in be waste of money for you. Maybe only for one time use?

You might visit some utube videos on derailier adjustment and derailier hanger alignment. Part Tool has good videos.

And bike shops have the tools. The easiest but pricier way to fix it. Let them check it out.