Hello @SamB12 ,
If the majority of your contacts utilize Apple Mail, then your increased open rates may partially be caused by this. Apple's newer privacy policies regarding emails includes pre-loading images, which would also affect the tracking pixel inserted into each sent email. For more info about Apple's privacy policy updates and how they affect campaign reporting, I'd advise checking out this article in our Knowledge Base.
It can also come down to other factors as well, such as increased seasonal email responsiveness from certain contacts, the size of lists you're sending to, the topics and subject lines of the campaigns being sent, and more.
See also:
How opens are tracked
Improving email opens
... View more