@blockly/plugin-serialize-disabled-interactions 
A Blockly plugin for the JSON serialization system that serializes blocks which are not deletable, movable, or editable.
When to use
For Blockly versions >= v9.3.0
This plugin is being deprecated, because serializing these disabled-interaction attributes is now handled by core in versions of Blockly >= v9.3.0.
If you had previously used this plugin to serialize workspaces, you should use v3.0 of the plugin. This version will deserialize the old saves, but it will no longer serialize the disabled properties (since that is now handled by core). Once all of your saves have been "cleaned" you can safely remove your use of this plugin.
For Blockly versions < v9.3.0
This plugin was created because the old XML serialization system supported serializing these disabled-interaction attributes, but the new JSON system did not (for versions of Blockly < v9.3.0). For more information about why this was, see this forum post.
In v9.3.0 this was changed to fix https://github.com/google/blockly/issues/6793.
It is strongly recommended that instead of using this plugin, you upgrade to a version of Blockly >= v9.3.0. However if that is not possible, you can use v2.0 of this plugin (as v3.0 does not actually serialize these attributes).
Note that this plugin is being removed in the future, so by newly installing it now, you will be introducing a dependency you will be forced to remove in the future if they you to remain up-to-date with core Blockly.