The latest release HTML at https://semiceu.github.io/MLDCAT-AP/releases/2.1.0/ show the respec error on top right corner, as well as loads many (devel/debug) css/js scripts which delays loading the page. These are helpful when the document is in draft form, but when the document is finalised the export feature should be used which removes all these and streamlines the HTML document to a 'publication ready' state.
See https://respec.org/docs/#static-snapshots for instructions. Do this manually by clicking on the ReSpec button on top right corner and export or use the CLI tool to export this.