Richard Thaler described the phenomenon: we keep separate "accounts" in our heads and apply different rules to each. A $1,000 bonus gets spent cheerfully; $1,000 of salary gets managed carefully. It is the same money.
The most expensive version is holding $8,000 in a savings account at 0.5% while carrying $4,000 of card debt at 19%. On any balance sheet it is a serious error; mentally they are two different accounts, and the "savings" one feels untouchable.
Not all of it is bias, though. Labeling money is also a tool: an emergency fund works because it is mentally sealed. The useful distinction is whether the label protects you from an impulse or hides an arithmetic comparison from you.