I notice the demo has had an update since I last checked, so I am grabbing that.
Though one hopes GOG will do the right thing and not remove the demo from our library, for those of us who have already acquired it.

GOG has removed at least one demo from users' library before.

Yes, and I am hoping they will do the right thing and not do so again.

Hello!
Removed from store:
2024-02-14
1671161730 Slave Zero X Demo

2024-02-15
1300475749 Japanese Drift Master Demo

Though still in your GOG library if you already had them.

And it seems Japanese Drift Master Demo has already had another update.

Another full release casualty!
BUT! still in library:
Removed from store 2024-02-22
1787461993 Rail Route Demo

Removed from store 2024-02-26
1754562354 We Are Not Alone Demo

On the Steam for full game: Planned Release Date: 28 Mar, 2024

Pocket Waifu Rekindled DEMO is available on GOG now.

New Demo:

https://www.gog.com/game/roboplant_demo

New Demo:

https://www.gog.com/en/game/helping_the_hotties_demo

New Demo:

https://www.gog.com/en/game/craftomation_101_demo

Currently no offline installer download links, in my online GOG web page library (i.e. browser link).
And of course, it is the weekend, so likely no fix until Monday ... as usual ... becoming quite the habit lately.

New Demo:

https://www.gog.com/en/game/moons_of_ardan_demo

Between Horizons Demo is available on GOG now.