I don't really think Lemmy.ml will have very good retention of new users. Because:
New users will mostly come from reddit or mastodon.
Most users of reddit and mastodon willing to leave are anti corporate, anti authoritarian, anti-war, pro human rights.
A lot of posts that you see on Lemmy (either from Lemmy.ml or lemmygrad) are pro-russia, pro china or anti-western to the point of being really annoying. Its not fun to talk to people without a hint of nuance.
So it is not surprising that new users will get turned off by this and leave (or move to beehaw).
I confess to trying and then leaving lemmy.ml in a huff because I allowed myself to get dragged into an argument with some asshole. I came back (to Beehaw) when I heard about a potential reddit exodus, and thought I'd give it another chance.
You don't like reading 6 paragraphs of mental backflips explaining how it's actually the US who needs to stop the aggression so we can have peace in Ukraine??