I'd be surprised if it was less than 16, especially as All Stars really dragged in the final weeks - although that was there own fault for having the triple eviction. Should at least have ended that with one of the three going back in. A 7th July start though probably means a 10-11 week run, so it is a significant cutback.
I see Love Island is also premiering the same night (the other 90 minutes I guess) so they'll be running side by side again. Given the ratings of it pretty clear CBS just keep hold of it so it isn't competition for Big Brother, though it would probably be better suited on The CW or Paramount+.