Error in PageSpeed report

Could you point me in a direction to resolve the following issue. This shows up when running a PageSpeed report for this page https://www.mnvphotography.com/

“Ensure text remains visible during webfont load
Warnings:
Lighthouse was unable to automatically check the font-display value for the following URL: https://www.mnvphotography.com/wp-content/plugins/foobox-image-lightbox/free/css/font/foobox.woff.
Lighthouse was unable to automatically check the font-display value for the following URL: https://www.mnvphotography.com/wp-content/plugins/foobox-image-lightbox/free/css/font/foobox.woff.”