It tends to also happen on Archipelago maps with high Sea (and low Resources). The game sometimes struggle to delimit well-defined continents with those settings. You sometimes end up with some scattered islands being their own continent.
The number of Luxury resource types is linked to continent: 4 types per continent. The number of continent is linked to map size: 1, 2, 3, 4, 5 and 6 continents on Duel, Tiny, Small, Standard, Large and Huge. A map with a lot of water and few landmasses ends up to easily get those 1 luxury to Monopoly, as the game needs to delimit those continents in some way. That is why there are sometimes a nonsensical continent cutting a landmass, including far away lands, or even some lone mountain / wonders out of nowhere. I think this is what happened on your Splintered Fractal: a lot of water and some odd continents delimitations.
It leads to a problem: early access to 25 GPT due to early monopoly. As tiny continent is easier to take over than bigger one, starting on tiny one allows for a quick and early 100 GPT, which could be quite unbalanced as it kickstarts and snowballs way too hard to any victory.
It is no secret that the Monopolies & Corporations
game mode is unbalanced. Not only because it is achievable to get an insane early GPT per turn just because you started on two joint tiny continents with the only coast with sea resources (as I suspect you had). But also because they made the Tourism modifier scale with the number of Civilization in the game.
I believe the insane Tourism modifier was an unfortunate and unintended mistake. My hypothesis is the following: I suspect they couldn't implement a Tourism modifier which would not apply to a Civilization sharing the same Luxury resources. They tried to circumvent the problem by adjusting the Tourism modifier by a X/Y ratio, X being the number of Civilization without the Resources, and Y the number of Civilization in the game. This sounds nice: instead of having +25% with 4 civilizations out of 5, we will have +20% with all 5 civilizations instead, which achieve at roughly the same results. Except the messed up, and they forgot the Y in the X/Y ratio: we have now +100% with all 5 civilizations instead!
A concrete example: we are on a 12-player game, enjoys a 6/9 resources monopoly with an Industry with 3 other players also owning the ressources. Currently, the bonus is +144% Tourism as 3% (Industry) × 6 (# of Resources) × 8 (players without the resources) = +144%. But it should have been 3% × 6 × 8/11 = +13% Tourism modifier.
In case we have the full monopoly of 9/9, instead of 3% × 9 × 11 = +297% Tourism modifier, it should have been 3% × 9 × 11/11 = +27% Tourism modifier.
It doesn't solve the insane GPT for early Monopolies though. Maybe they made a double mistake: maybe they switched the GPT and the Tourism modifier formula. So it could have been something like that:
- Tourism: +5%, +10% and +25% for a 60%, 75% and 100% monopoly.
- Gold: When under a Monopoly: 1 Gold per improvement, up to 3 Gold per improvement with an Industry or Corporation. The Gold output is reduced if a Civilization has not been encountered yet, and if a Civilization also own that Luxury resource.