As a crude measure, I say a 7% mortgage rate is the inflection point where it really makes a dent in households budgets. Why I say this, just before covid banks were stressing testing borrowers at around the 7% mark so this will be the majority of borrowers. We have to acknowledge the smaller pool of borrowers that took out lending between mid 2020 to late 2021 i.e the concentration of risk. Not so much stress testing, but more so to do with negative equity i.e if they had to sell.
The obvious reasons why it is crude is because people have had payrises since, however that has been offsetted by inflation. But in short people who started borrowing for their mortgage further way back will be relatively better off.
A larger proportion of income will be assigned to the big three items - accommodation, food and transportation.