Hello,
We found that issue was caused by Variation Swatches for the WooCommerce plugin. If the plugin is enabled then the opacity option is hidden https://prnt.sc/KtN8cbVarNB9
Contact the plugin author and ask them to improve the plugin code to avoid this affecting of the theme option and apply code for the plugin fields only.
Disable the plugin if you need managing of that option till they fix the problem.
Regards