After testing the new setup, I believe that the file block-library/style.min.css is not necessary when building a site from scratch with GenerateBlocks Pro. Currently I still use the old image block and the spacer, but it can easily be replaced with the various formatting options in GenerateBlocks Pro and the new image block is much more powerful. Eliminating block-library/style.min.css and inserting a few lines of CSS for the old images and the spacer brought my LCPs to green in PSI on most of my pages, even having a lot of JS originated by Ezoic Ads.