That is a very interesting topic

cannot but add my 5 cents
If we judge trends by what brands and influencers push, I’d say that the stacks are still big, and the pieces being stacked are getting chunkier, or a mix of chunky and dainty. Stacking is a lot about making jewelry more personalized even if you purchase from several well known brands.
As per more particular trends, I’d say it’s a lot about stones these days. Widely using stones like morganite, malachite, carnelian and more rare ones in fine jewelry became common not so long ago in my view, but it is to stay for long probably.
I also see many short term “demi-fine” jewelry trends. I.e. at the moment there are a lot of enamel pieces, “wabi-sabi” pieces with handmade feel to it.
What people wear in their majority in fact, as you all say is a different story. They wear a lot of basics and reach out for statement pieces that can be either bold jewelry, costume jewelry or branded jewelry. Watches are clearly losing popularity.
I believe that stacking will be forever popular, as jewelry, even demi-fine, in many cases are pieces with sentimental value. This “amulet” concept is pretty much “in your face”, but its idea is clear - people love collecting memories and having them on. Like Pandora was super popular - with more expensive pieces is just works in slightly different ways.