I think that the initial (rather snarky) comments were rather unnecessary. Let's remember that this is community for folks of all skill levels.
Raptiye wrote: ↑
Mon Feb 22, 2021 2:32 am
With the ctrl + u feature, many special bb codes and plugins on my site appear. How can I prevent it from appearing? Ty.
Crtl+U gives you the page source - that is to say, the code that the browser is using to display the page. As has been said, if you get rid of that code, then the page will also not display. In effect, what you're asking is whether there's a way to send the code to the browser (to display the page) while also not sending the code to the browser.
You could obfuscate the code a bit, to make it more annoying to copy, but ultimately all of this will be defeatable, because the code must be public in order to display the page.