Are there different ways to try to determine geolocation?

Today I connected my VPN to a server in Taiwan.

A few "what's my ip" websites claim Taiwan as my geolocation (IP shown matches VPN IP).  

Two "what's my ip" websites claim Singapore (IP shown matches VPN IP).

Tixati shows flag for Romania (IP shown matches VPN IP).

As best as I can determine I do not have any leaks.

How does geolocation work and why would these all be different?

This is not the first time I've seen this, it has been a somewhat regular occurrance for years.

Thanks for any info.

There're 'geolocation' databases traded by companies for IP addresses, much like real GPS geolocation tracking is traded (collected by free or not so free phone apps) or your browsing profile sold to advertisers. The goal is to identify what country/region/city an IP corresponds to. For example Google might track what addresses you view on Google Maps (your home) and record it for their in-house IP geolocation.
There are commercial providers but some databases are free and the quality reflects that. Yes Tixati's used database isn't very good and sometimes reports different countries for one peer but IPv4 vs IPv6 address. It is possible your VPN provider is deliberately faking its location (e.g. directly contacting some providers to 'correct' the geolocation)

To exclude any possibility of Tixati leaking actual traffic (not the DNS queries), go to network connection settings of Tixati and select the IPv4 & IPv6 network interfaces at the bottom. This is called network binding.