This isn't a new problem. I was doing some classic iPod research a while back, looking back on mid-00s hardware research. Some knowledge was present only in IRC chat logs, and some is surely lost to the sands of time. Similar story with PDA hacking.
The knowledge still needs to be transferred to wikis etc. so that it can be preserved long-term.
There were many times when I would have been lost without the Internet Archive. And more than once it was because of discontinued platforms on MS.
Knowledge in forums or now Discord has a shorter half-life until it's gone completely.
That's sad.
In a fresh and new project. But how will it look in 5 years when the user numbers are smaller because of other new projects?