Read carefully, it’s a bit subtle.
On AliExpress, when you click Account->Sign In, a pops up appears and you have about 1 second to click the Sign In button without any further complication, but that’s only if your username and password were auto-filled fast enough.
If you wait 1 second or so before hitting the Sign In button, a security slidebar appears and, when you slide it, you have to enter a 4-letter captcha on top of that.
Chrome auto-fills the username and password so fast that you have time to click the login button before the slidebar appears, good.
Brave doesn’t fill the password field fast enough or at all (= before the slidebar appears) and you have no choice but to slide the slidebar, which also forces you to enter the captcha, all of which is a pain when you consider that Aliexpress doesn’t keep you logged in for more than a couple of minutes.
Here is a video showing first logging in Aliexpress on Chrome and then on Brave