There is an API version of Google Pagespeed Insights that provides a very detailed breakdown along with links on what they are looking for in each point to get that individual metric up. I highly suggest trying it out so you can pinpoint what the real issues are. Link:
https://developers.google.com/speed/...v5/get-started
For example, the background and foreground contrast ratios is one of the points that can drive you nuts if you don't know the metric they are looking for:
Weight: 3 BACKGROUND AND FOREGROUND COLORS HAVE A SUFFICIENT CONTRAST RATIO
Score: 0 (Value: 0)
Comment: Low-contrast text is difficult or impossible for many users to read. [Learn more](
https://web.dev/color-contrast/).
WG