Serve resources from a consistent URL

I am getting the following recommendations from the GTmetrix speed test:

1- “Serve resources from a consistent URL” this one is solved by disabling Smush Pro “WebP conversion” but in this case, images won’t be converted to WebP. Would you please help me solve this issue without disabling the “WebP conversion”?

2- “Leverage browser caching” for this one I am trying to solve by activating Hummingbird caching but I get this message “Hummingbird detected an advanced-cache.php file in wp-content directory. Please disable any other caching plugins in order to use Page Caching.” However, I can’t disable this file as I am hosting on wordpress.com and I don’t have access to files.

Would you please help me to solve this issue too?