If you don't instantly recognize this sort of vindictive, over-the-top display of actively cutting off someone's contact with the outside world, count yourself extremely lucky.
In high school I bought a Nintendo DS "game" on my dad's eBay account while "grounded for life" and used the homebrew AOL instant messenger app to message my Halo CE clanmate boyfriend 🫡 served my time in fundamentalist hell, reporting in!
The gratuitousness really paints a picture of hatred & abuse. If I didn't want my kid to have their phone, I'd simply lock it in a drawer, or factory reset it & sell it, but the over the top act of "drowning" it in simple syrup really make me afraid of the behaviors they aren't willing to admit to.
They are destroying an expensive piece of electronic equipment because they can’t take away the phone themselves. They can’t even have a discussion about phone use with their children. That’s says a lot about them without even getting to the transphobia.
These same people will be bawling 'Why won't my children talk to me???!' as soon as they're grown and leave home, and I can't say I feel sorry for them.
I was regularly grounded and barred from non-school activity as part of continual failed attempts to treat undiagnosed ADHD (inattentive type) through punishment. I shudder to think how my parents would have treated internet access.