I used to be a patent examiner and provisional applications were filed to secure a “prior art date” before everything is finalized, and when I was there had to be followed up within a year with a regular application and only the processes described in the provisional get the provisional date.
You could file a new application in addition to older ones to add processes but the new added stuff gets the new filing date while the already described stuff gets the older date.
And it regularly took 2-3 years for an application to become a patent, and that was a relatively quick one without much back and forth, our backlog to even first look at an application was 18months. I was working on applications that had been ongoing for 5+ years after first being picked up by an examiner. It’s not important when the application became a patent, it’s important when it was filed and what it contained.
I haven’t looked at the specifics in this case (I really don’t miss being an examiner), but patent filing date and prior art dates are complicated and of course apple is going to try and make it sound like they didn’t infringe and masimo is going to try to make it sound like they did. Apple playing games with wording and product release dates is not really relevant. If apple developed the technology they can show their notes and get a prior art date before the masimo provisional application, because it didn’t just show up in their watch the day it was released.