Quick and dirty version for uBlock Origin:

  news.ycombinator.com##tr.athing:has(a[href*="medium.com"])
  news.ycombinator.com##tr.athing:has(a[href*="medium.com"]) + tr
  news.ycombinator.com##tr.athing:has(a[href*="medium.com"]) + tr + tr.spacer

If somebody can improve this, please share.