`530 Login incorrect` on correct credentials

[crowbait]

Describe the bug basic-ftp (or, technically, the server) fails with 530 Login incorrect upon being presented with correct credentials. This happens for three different servers (out of three tested). FileZilla has no problem connecting to either of those with the same credentials.

Example code

const { Client } = require("basic-ftp");
const ftp = new Client();
ftp.ftp.verbose = true;
await ftp.access({
  host: env.ftphost,
  user: env.ftpuser,
  pass: env.ftppass,
  port: 21,
  secure: true,
  secureOptions: {
    checkServerIdentity: () => undefined
  }
});
console.log(await ftp.list());

Console output

Connected to xxx.xxx.xxx.xxx:21 (No encryption)
< 220 xxxxxxxxxxxxxxxxxx

> AUTH TLS
< 234 AUTH TLS successful

Control socket is using: TLSv1.3
> OPTS UTF8 ON
< 200 UTF8 set to on

Login security: TLSv1.3
> USER xxxxxxxxxxxxxxxxxx
< 331 Password required for xxxxxxxxxxxxxxxxxx

> PASS ###
< 530 Login incorrect.

FTPError: 530 Login incorrect.

Which version of Node.js are you using? Node v23.7.0

Which version of basic-ftp are you using? basic-ftp v5.0.5

Additional context The servers tested all run on different FTP servers (as in, the software), management solutions AND even operating systems. So it doesn't seem to be some quirk with some server setup.