some time header css and js not loading
Please, turn off all of the plugins, refresh your cache, and check if the problem persists.
Moreover if you use a child theme, switch to parent, and recheck it
It looks like some cache software on your website is held not correctly.
we have checked with one-by-one plugin deactivating. then I can found the issue came on elementor pro plugin side. But we can't deactivate elementor pro plugin. because we have completed the site development.
Does that same happen when only Elementor and Elementor Pro plugins are enabled? Maybe it's in conflict with other plugin.
I can assume, that Elementor and Elementor Pro are compatible with Betheme and it should not make that issues.