We can use the information currently available to determine where GOG scraped its data. My guess is.... here!
https://www.igdb.com/games/doom--1
(https://www.igdb.com/api)

It also has all of the stupid things like this:
https://www.gog.com/dreamlist/game/mickey-s-blast-into-the-past-1995
https://www.igdb.com/games/mickeys-blast-into-the-past

It is the sales blurb used everywhere

https://gameroo.co.uk/game/doom--1
https://kotaku.com/games/doom--1
https://www.igdb.com/games/doom--1
https://www.backloggd.com/games/doom--1/
https://gamelib.app/games/doom--1
etc
etc
etc

As long as the web address links to a page ending in doom--1, then that blurb shows up. And yes, doom--1 points to the switch version. Just showing that usign a scrpaer with not controll ends up with silly results.

Aha. That would also explain why most of the obscure shareware titles I wanted listed aren't there.

Dragon Quest (Warriors) VII has a typoo in the name:
https://www.gog.com/dreamlist/game/dragon-ques-vii

Scrapland Remastered and Fallout London show up on the 'unreleased' filter even though both are listed as Released:
https://www.gog.com/dreamlist/?show_only_unreleased=1&sort=global_wishlist_last_voted_at&order=asc

Daggerfall Unity is delisted and now just redirects forever instead of linking to a game page:
https://www.gog.com/dreamlist/game/daggerfall-unity-2014