The difference is, that most Apps does read your clipboard when you start the App to check, if there is some relevant information for that App and part of the r

The difference is, that most Apps does read your clipboard when you start the App to check, if there is some relevant information for that App and part of the reason why is that you can not set default Apps in iOS (in iOS 14 this will be possible for browser and mail). A browser for example does check if you have a URL to offer you to open it. Apollo (a Reddit client) for example does check if you have a Reddit URL in your clipboard to offer you to open it. Or a banking App does read it to offer you to make a transfer to a IBAN you have in your clipboard. But TikTok did read the clipboard every few keystrokes you did on your keyboard. That’s a huge difference. Of course you can’t say for sure that all the others didn’t do anything crazy with the data from your clipboard but they at least have a valid reason to read it.