Would the requirement for employers to pay to hire European citizens apply in case of employees with settled/pre-settled status?
The requirement to apply for a work visa, and for your employer to have a sponsorship licence, only applies for new arrivals from 1 January 2021, so it will not affect EU citizens resident in the UK before this date. You can continue to work and change jobs freely as you already live here. During the first six months of 2021, up to the 30 June 2021 deadline for applying for (pre-)settled status, employers should not ask for proof of (pre-)settled status. They should treat both groups of European citizens the same and only ask to see an EEA/Swiss passport or national identity card.