Even with Premium WP Fastest Cache, PageSpeed keeps pointing the same problems

Hello!
We′ve got the premium version of the plugin and enabled all the options but PageSpeed keeps pointing problems with critical inline css, lazy load, etc.
Is it possible that the plugin is not acting as it should in our website?
I tried to disable and enable again to see if it would do any diference but it is still about the same.
What could I do?

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