Codex WordPress recommends another way to create a Child Themes.
Note that the previous method was to import the parent theme stylesheet using @import: this is no longer best practice, as it increases the amount of time it takes style sheets to load. The correct method of enqueuing the parent theme stylesheet is to add a wp_enqueue_scripts action and use wp_enqueue_style() in your child theme’s functions.php.
You can fix this in your Сhild Еheme? Or Can You provide instructions on how to proceed with that?