If you run Bitwarden eg. in Proxmox LXC you need to make sure Bitwarden start automatically. Create a configuration file in /etc/systemd/system/bitwarden.service with the following contents.

[Unit]
Description=Bitwarden
Requires=docker.service
After=docker.service

[Service]
User=bitwarden
Restart=on-failure
ExecStart=/opt/bitwarden/bitwarden.sh start
ExecStop=/opt/bitwarden/bitwarden.sh stop

# Script starts docker images and ends
Type=oneshot
RemainAfterExit=true

[Install]
WantedBy=default.target

Enable it, start it and check the logs.

systemctl daemon-reload
systemctl enable bitwarden
systemctl start bitwarden
journalctl -f -u bitwarden