Apple has been using + way before Disney. Apple care+, iPhone 6 Plus and I’m pretty sure they had another plus product or service in the 2000s or earlier that I’m forgetting right now. Edit: it was the Mac plus from 1986.
I’ve always associated “plus” with Apple, not with Disney.
https://en.wikipedia.org/wiki/Disney%2B "Disney+ was launched on November 12, 2019"
https://en.wikipedia.org/wiki/ICloud "In June 2021, Apple introduced iCloud+..."
https://en.wikipedia.org/wiki/Fitness_(Apple) "Apple Fitness+ is an ad-free video on demand guided workout streaming service announced during Apple's September 2020 Special Event"