No matching base image for an alpine based image

[PeterDaveHello]

Here is my Docker image:
https://hub.docker.com/r/peterdavehello/ipinfo.tw/

And it shows no matching base image here:
https://microbadger.com/images/peterdavehello/ipinfo.tw/

As you can see in the Dockerfile source code on GitHub, it's based on Alpine:
https://github.com/PeterDaveHello/ipinfo.tw/blob/master/Dockerfile

I assume it's a famous base image, not sure why isn't recognized, or it's something like #50?

Many thanks.