There's a fair amount of enthusiastic or expert communities that remain the most vibrant in their IRC edition.

I recently looked for an active chat for hobbyist/DIY EE stuff, and I joined around half a dozen Discords and they were all nearly completely deserted. Part of it is that each individual Discord aims to be a complete lifestyle, replate with completely redundant #general rooms and what not - it's too hard to sustain that kind of thing.

##electronics on Libera, meanwhile, is alive and kicking every time of the day.

I've made similar experiences with non-tech topics like e.g. cycling.