Where are those giveaways coming from?

from a shady extension

Masafor says, " links to that site aren't allowed at sg".
Sorry, I removed it.

Fanatical : The Magnificent Mystery Machine

From a previous Humble Monthly :) I think May's.

Fanatical's Mystery Bundle

Mystery fanatical or Humble Tinybundle (already end)

Fanatical kalypso bundle

It's also one of the possible keys of The Magnificent Mystery Machine (Fanatical)

https://www.steamgifts.com/discussion/AUxx5/fanatical-assemble-bundle

Fanatical Mystery

Indigala bundle: https://www.indiegala.com/radical-mix-indie-steam-bundle

Looks like Fanatical have it on discount in their store

And it's also in The Magnificent Mystery Machine (Fanatical)

Would like to know also

Both from Fanatical Mystery

the description says they're from the dev.

https://www.steamgifts.com/discussion/tHaRx/fanatical-fugitive-bundle

https://www.steamgifts.com/discussion/tHaRx/fanatical-fugitive-bundle

I think it was an Indiegala giveaway:
https://www.epicbundle.com/article/steam-key-for-free-the-dark-stone-from-mebara
Before they stopped doing steam key giveaways.

It was in many many bundles a couple years ago, including one of the big "$1 bundles" from Bundle Stars/Fanatical, so my guess is they are leftovers from those old bundles.

https://www.steamgifts.com/discussion/PgFsE/bundle-stars-dollar-monster-bundle
1 tier, 50 total
1 dollar, 50 games