Is Etc/Unknown a valid timezone?

I'm getting my website visitor's timezones usings Intl.DateTimeFormat().resolvedOptions().timeZone, but this is often returning the timezone Etc/Unknown.

Is this a valid timezone? Do you have any further information about this timezone?

Thanks

Etc/Unknown timezone states that timzone information cannot be determined based on user's preferences. To overcome this, you can use a default timezone, or allow user's to manually select it. You cannot rely on this method alone. You can use alternative methods like IP Geolocation.