Description:

We use

jQuery( window ).load( function () {
	jQuery.neveMetabox.init();
} );

in /assets/js/src/metabox.js
jQuery(window).load was deprecated in 1.8, and removed in jquery 3.0 and we should probably use it as an "Event Handler Attachment":

jQuery( window ).on("load", function() {
        jQuery.neveMetabox.init();
});

Reference:

Reported here:
https://wordpress.org/support/topic/jquery-migrate-helper-warnings-encountered-8/#post-13522104

Technical info

• WordPress version: 5.5.1
• Theme version: 2.8.2