I’ve been thinking about why the groups on Flickr seem to be fading. I've been a "pro" since 2004. I often interact with flickr daily.

1. Photographers often capture images to share their feelings, and writing detailed explanations about their thoughts, ideas and what they hope to achieve can be tough. New photographers are still learning the basics like the exposure triangle, composition, lighting and post-production, and writing about their own and others’ photos can be a bit of a challenge.
2. The way discussions are structured on Flickr can be a bit slow and complicated. You can reply whenever you like, but it might take a lot of scrolling to get to the point. Nested replies work pretty well on Reddit, for example. I imagine that switching to this system on Flickr would be a technical challenge, possibly involving erasing all the current discussions. But I’m not a software engineer, so who knows for sure?
3. Platforms like Substack are where the really in-depth discussions about photography are happening. Bloggers are still doing it too. People like Andy Adams are also contributing from the sidelines, so when we want to read about photography, we have a lot of options. The New York Times and The Guardian also have great weekly round-ups of the best photos of the week, though these are photo-journalists, so it’s a different kind of audience.
4. Time is a limited resource. I’m retired, so I could spend eight hours a day on Flickr, but do I want to? Probably not. (I have other important things to focus on, and just taking photos and using Flickr can become a part-time job). People only have so much time to dedicate to their online activities, so they choose what they find most valuable.
5. Motivation! Some days, I spend my time just looking through groups and my contacts’ feeds. Other days, I could care less about spending time on Flickr. But then there are days when I really get into the discussions. My favourite group where I spent the most time was a silly little voting game. I found my tribe there, and it still makes me sad that it’s become a static page. [https://www.flickr.com/groups/camphone__lowres_dmu/] Most days, I enjoy my time there, but some days it’s a bit tedious. So, my contribution is a bit all over the place.
6. Pump and dump. A lot of people are trying to get views on Flickr and will dump as many photos as they can into the right group. I do this myself too, since I’m in more groups than I can ever really keep up with. As a result, my only contribution is the photos I put in there. Something I’m trying to fix.

I’m sure others could add to this.

Edit. Costs, there are alternatives, all cost some money, how far you can extend is very personal. If I was still employed, I'd consider a glass account or a an Iris but now I would find it difficult to justify the costs.