This is legislature that has been enacted in 16 states; here is the current status of the bill across the US. https://www.nationalpopularvote.com/state-status

https://crsreports.congress.gov/product/pdf/LSB/LSB10515

Supreme Court held that states may punish or replace presidential electors who refuse to cast their ballots for the candidate chosen by all voters of that state. Pretty much saying that it is a law that electors need to provide all votes to keep the election fair/just. Furthermore, in Chiafalo vs. Washington, it states  that Washington could impose a fine against electors who violate their pledge to support the candidate chosen in the states popular vote.

This Supreme Court case ruled that “unfaithful presidential electors” can be punished or replaced if they refuse to cast their ballot for the majority favored candidate of the state. The elector pledges to vote for the candidate that wins the state’s popular vote, but some choose to be discursive and vote independently. This document goes over the Supreme Court’s ruling and its broader implications for the electoral college.

https://crsreports.congress.gov/product/pdf/LSB/LSB10515