It is less complicated than it looks, once the terms are clear.
The change has been coming for a while, but it only became obvious this year.
Where the confusion starts
The exceptions matter more than the rule, and there are three of them. The figures move about, but the direction has been the same for three years.
What to check first
There is a deadline involved, and missing it costs more than the difference. The figures move about, but the direction has been the same for three years.
Where to go from here
Nobody is required to explain this to you, which is half the problem. Most of the confusion comes from two terms that sound alike and mean different things.
None of this is urgent, but it is worth an hour before the next renewal.