It doesn't help that they have started placing content from more obscure subreddits onto people's front pages seemingly randomly, so people wander into places and have no idea what the culture is they are contributing to and add content which is wildly out of place.
To get subject matter discussion which is reasonable I have been wandering back to bespoke forums, which isn't necessarily bad, but they still have a lot of issues. A lot of other content has moved to discord, but I won't get into how I feel about that.
i certainly didn't help; i used shreddit to overwrite then delete my posts.
Some Reddit metrics might've hardly noticed the blips, but if they had metrics for early-Reddit qualities, such as for smart (or clever) comments, helpful information, humor, or goodwill... I suspect those would be bad. Where they're not bad might be non-frontpage subs that are still cruising along with their earlier communities. But those communities started in earlier Reddit, and I suspect that today would not have started there.
Those had already tanked before any API changes.