ssling: Because they never are unless it's day one launch sometimes.
flanner: but why? so which type of games si upcoming corner made for? only for new? or old less than 10 years.. i dont understand the rule
Mostly it's down to whether the publisher or developer
allows GoG to announce this or that game (old or new, doesn't matter) as coming soon via the upcoming section.
Why that is, you ask?
Because most publishers/developers don't want the public to know that in addition to DRM'ed releases of this or that game on the other platforms there's also going to be a DRM-free release available on GoG.
And DRM-free, in their mind, still equals illegitimately distributed copies which allegedly prevents maximisation of initial sales. While, of course, being blissfully ignorant of the cracked scene-releases out on the webs the very same (launch) day, sometimes even earlier than that, anyway.
For older classic titles GoG might not announce them deliberately (even though they would have gotten the permission to do so), in order for the unannounced "out-of-the-blue" release to be more effective and surprising. Like the recent release of Skyrim or back in 2019, the completely unexpected re-release of the original Diablo.