vsftpd stops right after starting, adds spam to config file

So this is how I run it and what it does:

# podman run -t --name "vsftpd" -p 20:20 -p 21:21 -p 21100-21110:21100-21110 -v conf-dir:/etc/vsftpd -v files:/path/to/files    -e FTP_USER=ftpuser -e FTP_PASS=1234567812345678 -e PASV_ADDRESS=127.0.0.1 -e PASV_MIN_PORT=21100 -e PASV_MAX_PORT=21110 -a STDERR -a STDOUT --rm vsftpd
    *************************************************
    *                                               *
    *    Docker image: fauria/vsftpd                *
    *    https://github.com/fauria/docker-vsftpd    *
    *                                               *
    *************************************************

    SERVER SETTINGS
    ---------------
    · FTP User: ftpuser
    · FTP Password: 1234567812345678
    · Log file: /etc/vsftpd/vsftpd.log
    · Redirect vsftpd log to STDOUT: No.

After that, it just shuts down, nothing more. There is nothing on STDERR, so what's wrong here? One thing I noticed is that it adds the following wall of config variables to my config file with each restart:

pasv_address=127.0.0.1
pasv_max_port=21110
pasv_min_port=21100
pasv_addr_resolve=NO
pasv_enable=YES
file_open_mode=0666
local_umask=077
xferlog_std_format=NO
reverse_lookup_enable=YES
pasv_promiscuous=NO
port_promiscuous=NO

Any idea what's going on?

fauria / docker-vsftpd

vsftpd stops right after starting, adds spam to config file #83