Ok, so the big change in 3.6.0 from release notes:
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New: BIG CHANGE - updated the engine to apply all rules of a certain
type/customer by default. In order to apply the first rule that applies
it is required to group them in a parent rule
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What the php attempts to do is to group all rules into relevant parent rules so they still operate the same way. For example, you have these 2 rules:
Rule 1: Order rule for Everyone which gives a 10% coupon code if the order total is greater than $100
Rule 2: Order rule for Everyone which gives a 5% coupon code if the order total is greater than $50
Before 3.6.0, the first rule that applies will be processed.
After 3.6.0, all rules that apply will be processed.
After 3.6.0, in order to apply just one rule, you would need to create a parent rule where you attache both Rule 1 and Rule 2.
