TinyMCE editor is not holding any properties related to the table. The source code in the editor is not showing any changes made to the table properties.
There is a system property: "glide.ui.html.editor.extended_valid_elements" , which handles what elements are allowed on TinyMCE editor
It's value is set to below Value
Update the property , "glide.ui.html.editor.extended_valid_elements" to allow styles to be added to table elements by setting the below value to it: