Hello, Vedad07,
Thank you for contacting us and for using XStore.
Elementor and our theme use scripts to apply styles, so it takes some time while necessary scripts are loaded. You can enable the site preloader via Theme Options to hide that effect or try to speed up the scripts loading using a cache plugin https://www.8theme.com/documentation/xstore/troubleshooting/how-to-speed-up-my-website/ , and improve server speed settings.
Kind Regards,
8theme team