I think that forums in general are not as frequented any more as they used to be 10 years ago. It is a slow, ongoing process. And it is a pity IMHO.
This seems to be the case for GS in the same way as for another forum, for which I am moderating a sub-branch along with some I have now and then visited.
People shift to more fleeting media such as FaceBook, Discord, etc. In some ways, these seem to be more accessible, but IMHO they cannot match a forum as a resource. Another serious drawback is that FB, Discord and the whole damn zoo of them are extremely shitty about maintaining the privacy of their users. In fact, they take all possible measures to destroy privacy and to monetize their users' data. Reason enough for me to avoid them like the plague.
Moderation - or non-moderation - may also be a factor. If the correct balance is found for moderation, I find it beneficial. Many social media are hardly moderated at all, so that all sorts of lies, hate, and bull***t can be vented there in a misunderstood or outright abused understanding of "freedom of speech". Outrage does keep people longer on these media, so more money is generated from commercials, which is the business model. An amoral and harmful business model for society IMHO and another reason for me not to utilize such social media.
Is the forum dead? I do not think so.
Could it see more activity? I would welcome it.
Over the past years, GS has lost some of its more prolific contributors, some of whom went in anger.
This is regrettable.
In any case, this forum is as lively as YOU (i.e. anyone of us) make it.
von Marwitz