ProShow had official Style Packs (transitions/layouts). A "Vintage" pack likely contains film burns, light leaks, sepia frames, old projector shutter effects —very much the Instagram-filter aesthetic of 2012–2015, now genuinely retro.
"The Vintage Pack saved my business in 2017. I charged $500 extra for 'vintage styling' just by applying the Film Strip style to every 10th slide. It’s that convincing." –