A fake feeling of nostalgia for something old you didn't actually experience - like Instagram filters and throwback branding from before you could actually walk.
Fauxstalgia is sometimes used by folks who weren't born at the time to hark back about their experiences in the second world war, or used to remember a thing that didn't even happen such as the world before migration.
Karen aged 50: "Yes it reminds me how good it was in WWII when we didn't have transgendereds"