It’s cause PHP associates the if-then-else pair only with its immediate “else” option, not with the entirety of the line.

Let’s go by parts.

$a == 1 ? "one" : $a == 2 ? "two" : $a == 3 ? "three" : "other"

Is $a equal to 1? If so, we’re “set” to the value on the left, which is "one", if not then we’re set to the value on the right, which is $a == 2. $a is not equal to 1, so we’re set to the right value, $a == 2.

This replaces the relevant part, $a == 1 ? "one" : $a == 2, with $a == 2. So we’re left with:

$a == 2 ? "two" : $a == 3 ? "three" : "other"

Next, is $a equal to 2? If so, we’re set to "two", if not we’re set to $a == 3. The comparison is true, so we’re set to the value on the left, "two". The relevant part here is $a == 2 ? "two" : $a == 3 only, so it replaces it with "two" cause again, PHP is only associating with its immediate pair. So now we’re left with:

"two" ? "three" : "other"

Finally, is "two" truthy? If so, we’re set to "three", if not we’re set to "other". Since "two" is truthy we’re then left with "three".

It’s super confusing for sure.

both are dualboot with Windows for Gaming (nvdia gpu in both).

If you don’t mind the question, what games do you play? Have you tried gaming on Linux at all? Gaming works really REALLY good nowadays.