[vladvasiliu]

What do you mean "per-app in safari"? I'd like to turn it on globally, with a single exception: I want to be able to continue using shared photos albums with my two best friends.

I don't care enough about JS performance or, more generally, the mobile web, to want to disable it on safari, or even parts of it.

[n8cpdx]

You can disable lockdown mode in web views for specific apps. You do it in settings because those apps don’t have the usual Safari UI for configuring that.