I did not see a relevant effect. Small forum, only exists since two years and German language only. But in a very special niche, very active for the size and with high quality content. I invested considerable time to manually feed the Google index in the first year or so, after a while Google started to crawl very actively. So I reduced the manual feeding to almost zero, I only feed it with new special threads and pages with very high quality content into the search console manually. Most times it turns out unnecessary: today new threads on my forum are often indexed literally minutes after they are posted.
About 2/3 of new visitors of my forum come via Google. Other search engines are basically irrelevant - i.e. Bing has indexed way more pages than Google, still the traffic is not even 10% of what comes through Google. Also, there's not that many links leading to us from other webpages and thus only a very limited amount of visitors through that channel.
Search results and clicks have been on the rise constantly and still are. At a low level, but growing. Development of clicks over the last 12 months:
The rise has however slowed down a little bit over the last months. Average position did not really improve (rather became slightly worse) and impressions also rather went down a little than going up. But both not too dramatically and with volatility. July and August are a bit of an outlayer anyway due to holiday season.
In search console there are no relevant hints that I would have to improve anything. PageSpeedInsights complains about the size of the JavaScript - not much I can do about it. As my forum is small but vital, non commercial and has no ads I do not mind about traffic, ranking or new visitors much - I monitor it mostly out of curiosity.
The only interesting effect that I saw was a massive loss in indexed pages at the beginning of June: From 32xx pages I went down to 2700 all of a sudden for no obvious reason, so a loss of almost 20%. But from mid June on it started to build up again, also with a jump of a couple of 100 pages out of the blue and for quite a while now I am at over 3200 pages again - but there is no noticable growth, almost stuck, despite new threads getting posted.
Discover has never been a big thing for us and barely ever happend. This barely ever has however become a little bit more frequent in the meantime:
I do reliably get between 60-90 new forum members signing up every month and the average of signups per day has been slowly on the rise constantly since the two years that the forum exists. That's what counts in the end. Don't want to become too big anyway - would only create extra work.