The article actually mentions those: > [...] they use JavaScript to offer some of their functionality, like a password manager. Basically a 3rd-party browser

The article actually mentions those: > [...] they use JavaScript to offer some of their functionality, like a password manager. Basically a 3rd-party browser needs to use JS to offer any features or real benefit over simply using Safari. But as a TikTok user you have no benefit when all links open inside the app with tons of custom JS injected that seems to be mainly for tracking you.