My favorites are Cloudy Nights (USA) and Stargazers Lounge (UK).
https://www.cloudynights.com/index
https://stargazerslounge.com/
Cloudy Nights is the biggest and has a global membership though the majority are naturally from the USA. There are many sub-forums covering most interests. They are sponsored by Astronomics, an American retailer. The forums are very well moderated by volunteers from all over the world.
Stargazers Lounge is sponsored by First Light Optics and also is well moderated by volunteers.
Andy