electronic music production (hosted by elektron but discussion about other gear is accepted):

https://elektronauts.com

cycling:

https://velocipedesalon.com

https://forums.thepaceline.net

simracing:

https://simracingonline.co.uk

https://www.lfs.net/forum

https://www.overtake.gg/forums/

And a few others I visit less frequently but I won't mention because I have already leaked a lot of information :-)

I guess there are still a ton of forums that cover a wide variety of hobbies/interests.