Where to find the block id ?

Not sure exactly of the question but I just used this module for the first time and had to work out the steps.
I enabled the filter option "Embed Block" in my text format/editor.
My block was from a View - I "placed" this in "Auto hidden blocks".
In that blocks display I used Devel in the drop down to look at Variable under Load and see this:
[settings:protected] => Array [id] => views_block:last_updated-block_latest_update

And that is what to use in the text area {block:views_block:last_updated-block_latest_update}
Works a treat!

It's pretty simple, this module is nearly useless without this TOTALLY AWESOME patch that has not been merged.

Here it is:
✨ Embed Block CKEditor Enhancement Needs work

I'm contemplating forking this project so that we don't have to use the patch and can work on ckeditor5 compatibility and expect a tagged release.

    "drupal/embed_block": {
      "3225938 - Added CKEDITOR plugin functionality": "https://git.drupalcode.org/project/embed_block/-/merge_requests/2.diff"
    },