When creating/changing a rule that wasn't bannable/punishable before and someone does it because it wasn't bannable back then, you should only warn them. If they did it after a day or two when the rules was published then you can ban them. Banning someone because they broke a rule 1 hour or they are currently breaking since it was not bannable before after the rule was published is just wrong. People don't go like "Oh I'm gonna check the rules every 1 hour to prevent getting banned". Another example here is a store giving away free groceries and the owner reporting them to the police 2 days later because they stole and they changed the rules.
Simplify:
Don't ban someone for breaking a rule currently or 1 hour after it was published since people don't check them every 1 hour.
I personally agree 100% with this rule. Thats like issuing new measures against the coronavirus, not telling the people about it, and punishing people 30 min after it.