Well, duhh. But they are not paid the same. Or anything like the same. That’s how the Saudi thing works, at least at the moment; they are in a position to throw ridiculous amounts of money - even by Premier League footballer standards - at it in order to lure enough decent players there to give their league publicity. See LIV golf and no doubt other sport wash stuff of which I’m not aware.
If Serge is offered a Saudi deal, Forest will not have the slightest chance of matching it. Doesn’t mean he’ll definitely go, but it probably makes it pretty likely. After all, Jordan Henderson’s public stuff about LGBT+ rights didn’t stop him going…
In due course, if you are right, you’ll be in a position to list players who were offered a Saudi deal but opted to stay where they were. Especially at a middle ranking provincial club that’s likely to be fighting relegation every season for a good while. At the moment, I’d say that list is vanishingly short