I'm struggling to find a source that explicitly states what the rules will be from 2023 and onwards. All I can really find is this one, https://www.fotball.no/lov-og-reglement/spilleregler/spilleregler2/, but this has not been updated since January 2022, which is 5 months before the IFAB decided to make the 5 substitutions change permanent. That url seem to be pretty much the 17 rules from the laws of the game from https://www.theifab.com/, translated to Norwegian. So I'm assuming it just has not been updated yet for next year. I also can't think of a reason as to why they would revert back to 3 substitutions after the rules change permanently, having used 5 substitutions all throughout covid.