`Delicious Brains updated their Offload S3 plugin to v2.0 today (using paid version). After the upgrade, it appears Smush Pro throws the following error on the media screen. For now the only solution was to disable Smush Pro.
Fatal error: Uncaught Error: Call to undefined method Amazon_S3_And_CloudFront_Pro::is_attachment_served_by_s3() in /srv/bindings/6f3a7d2c922645849f736fcc2511a1f9/code/wp-content/plugins/wp-smush-pro/lib/integrations/class-wp-smush-s3.php:265 Stack trace: #0 /srv/bindings/6f3a7d2c922645849f736fcc2511a1f9/code/wp-content/plugins/wp-smush-pro/lib/class-wp-smush-helper.php(128): WpSmushS3->is_image_on_s3(6030) #1 /srv/bindings/6f3a7d2c922645849f736fcc2511a1f9/code/wp-content/plugins/wp-smush-pro/lib/class-wp-smush-resize.php(119): WpSmushHelper->file_exists(6030, '/srv/bindings/6...')
Also, while they didn't go into detail, the Delicious Brains folks did mention having received other Smush Pro related support tickets.