Those aren't really FOMO in my opinion, more like being curious about what the praise was about. It's trying new stuff, and rather healthy I'd say, even if you realize some of those really weren't for you in the end. Yeah, I had quite a few of those too.
To me, FOMO would be anxiety about stuff that you really can miss "forever" and regret afterwhile.
In games, it's weaponized with artificially limited stuff because whoever is pulling the string wants you to fear a missed opportunity and make an impulse decision.
It's stuff like preorder "bonuses" you will never have another chance to get otherwise, time-limited content, battlepasses, daily rewards etc.
One of the most pathetic recent example I can think of being Nintendo making the translation of a 1990 Famicom game available only for a couple months. "Quick, buy Fire Emblem now, before it disappears forever!!!"
Not sure I understand. Does it only count the first creature you scan on a planet? Or the first creature you scan at all?
I guess in both cases I'll wait for a fix, even if you get one chance per planet I don't like these odds.