The shift in behavior is interesting, but I believe we're spending a great deal of time on our mobile devices for multiple reasons. The devices are more powerful, screens are larger and the functionality provided by applications has improved greatly over the last 5-10 years.
How would you break your time up on your laptop/desktop vs. Mobile?
For me:
Work: 95% Laptop/Desktop and 5% mobile Social/Casual: 90% Mobile and 10% laptop/desktop.
I would also throw tablets under the mobile space.
5pm-to-bed tablet. Its small enough to hold, fast enough to do what I want.
24h phone for signal because they haven't released adjunct-device for android tablet despite having done it for adjunct iPad.
Social: 35% Laptop and 65% mobile
Passive consumption/doomscrolling/background media: 95% mobile and 5% laptop
Reading books: 60% Kindle, 30% laptop, and 10% mobile (the last two are because I've taken to reading webfiction on Royal Road).