After reading about this change, I checked a couple of client websites where the client had installed Imagify and enabled its webp setting.

75%+ of the webp images were larger than the jpegs they were created to replace.

Needless to say the webp setting was immediately disabled and I will be taking the plugin mentioned further up in the comments and converting it into a mu-plugin to be uploaded to all my client sites before upgrading to 6.1.