FIFA have given individual leagues across the world to continue to use five substitutions for the 2020/21 season and keep it a regular rule until August next year. The governing body passed the rule after it was agreed upon for it's fair use and positive feedback. However, with FIFA allowing the leagues themselves to decide if they want to use it, the Premier League have voted against the use of five subs for the 2020/21 season.
The idea of the rule was to protect player welfare and how it isn't expected that many clubs will have the financial backing to add to their squad depth, given the current circumstances.
The Premier League did alter their rules for the restart, allowing nine players on the bench rather than seven and allowing five of them to be subbed on, as opposed to three. But now, for the 2020/21 season, the old and regular rules will be in place.