Lifestyle creep
When spending rises to match each raise, so your income grows but your savings don't.
Lifestyle creep usually happens in small steps: a nicer phone plan, more takeout, a pricier apartment at renewal. None of them is wrong on its own, but together they can absorb a whole raise.
The simplest defense is to move part of every raise into savings or retirement before the first bigger paycheck arrives.
Example
A $335 monthly raise after tax with $170 sent to savings still leaves $335 − $170 = $165 more to spend each month.