This is also the case if your site has doubleclick ads or similar, they are the slowest part of the page by a significant amount. In my experience a site got a

This is also the case if your site has doubleclick ads or similar, they are the slowest part of the page by a significant amount. In my experience a site got a lighthouse score of ~50 with doubleclick ads enabled, and a score of 100 with my network ad blocker enabled. Truly infuriating that they penalize you for using their own solutions. And of course G has no support to speak of to help report or remedy the problem.