Schema added in the footer section is not showing in Google schema testers

it may be a cause of the WordPress plugin, which plugin you are using for faq schema scripts?
did you use an accordion?

most of the themes of the website provide footer script options like Kadence. Like my website has this option which I added on these pages FESCO, Ke-electric, and other pages of the website or you can use Rankmath accordion for FAQ schema.

header and footer plugin

Is this the plugin you are referring to: https://www.ads-software.com/plugins/insert-headers-and-footers/

If yes, I recommend asking at https://www.ads-software.com/support/plugin/insert-headers-and-footers/#new-post so its developers and support community can help you with this.