"The register_block_style() function used earlier allows developers to add a style_handle, a reference to a registered stylesheet. Themers can also add an inline style directly via the inline_style argument. For just a few lines of CSS, this works well.
In my own themes, I register block-specific stylesheets via the wp_enqueue_block_style() function — yes, the function names are terribly confusing. This was officially added in WordPress 5.9. It will only output the CSS when a block is used on the page. For example, I add a core-image.css file to house all Image block CSS. This is the method I recommend."

Hey Justin, I would love to hear more on how you setup / structure your FSE themes in the "Building with Blocks" series.