I'm a great fan of plugins which without bells and whistles simply do, what you expect and this plugin certainly is one of them. It allows you easily to create your own block patterns and use them as you like. The plugin is lean and the code clean. So far 5 stars.
So, why did I only rate it 4 stars?
I like to read the code of plugins, that I want to use on my client's websites. All functions do have a single line comment, but unfortunately in Japanese, which makes it difficult to read (i.e. I have to use a translation programm to understand the comments).
The plugin also doesn't seem to follow WordPress' coding standards, e.g. by using short array syntax and inline control structures.
Personally, I would have liked it better if the Custom Post Type Block Patterns menu was a submenu of Appearance. A remaining comment // 'menu_position' => 6 looks like the plugin author had some other position in mind, too.
Don't let these nitpicky comments fool you - the plugin does what it's supposed to and it can be used without hesitation despite these really minor flaws.
Thanks for sharing the plugin.