From the linked article, the vaccine effectiveness of 10 weeks factoid you mentioned is a bit incomplete. It only talks about effectiveness against symptomatic infections. The effectiveness is dropped to about 40% around 10 weeks for people with AstraZeneca and then Pfizer or Moderna booster, or Pfizer and then Pfizer booster, and to about 70% around 9 weeks for people with Pfizer and then Moderna booster.

There was insufficient data to estimate the effectiveness against severe disease.