Unable to download from S3 via browser, signed in with Account ID

Question

I have the following policy:

"Statement": [
        {
            "Sid": "Stmt1660020066047",
            "Effect": "Allow",
            "Principal": {
                "AWS": "arn:aws:iam::ACCOUNT_ID:root"
            },
            "Action": "s3:*",
            "Resource": "arn:aws:s3:::MY-BUCKET/*"
        }
    ]

I'm trying to access via browser (by signed in with the ACCOUNT_ID account) but I'm receiving the ACCESS_DENIED error, why?

If a put "AWS": "*" then I can see the files in the browser (obviously now they are public), but it's just to see that the policy works.

So I guess that even if I got "access" I can't see the files via browser.

Any hint?

NOTE: Public access block is already disabled.