@jefff1979 That particular website briefly uses "pointer lock". Meaning that when you move your mouse, it will not move the mouse cursor, and instead, the website can use your mouse movements for some other reason. Pointer lock is typically used by gaming websites, so you can move your mouse to make your character can look around, but the cursor never appears outside the edges of the website area, even if you move it far enough. When a website uses pointer lock, the browser shows a message telling you so, and that you can use Esc to exit it, except that website disables it again so quickly that the message gets hidden again.

Who knows why that website is using it, but likely it is part of their bot detection (if you have a real mouse and pointer lock actually works, you are less likely to be a bot?). Personally, I find it very weird, it almost looks like they are trying to be malicious and hiding your mouse to irritate you, except that is a well known bank, not some malicious website. So rather than malicious, they are just being weird.

Either way, when the website disables pointer lock again, this causes your system to move the mouse to some default location. Mine doesn't do that; for me it puts it right back where it was. But your computer/system chooses to move it.