Consider holdover. Although primarily used to refer to people from a previous administration, it can be used for anything that continues to persist beyond it usefulness.

A person or thing surviving from an earlier time, especially someone surviving in office or remaining on a sports team.
‘But in reality, Daylight Savings Time is an archaic holdover from a time when people relied on candles all the time.’
_Lexico

Consider holdover. Although primarily used to refer to people from a previous administration, it can be used for anything that continues to persist beyond its usefulness.

A person or thing surviving from an earlier time, especially someone surviving in office or remaining on a sports team.
‘But in reality, Daylight Savings Time is an archaic holdover from a time when people relied on candles all the time.’
_Lexico