First, let's check if you can open another domain on .dev TLD, like web.dev, if not then:

Seems like you have some mapping for .dev TLD. Assuming based on your mention of Safari, that you are using Mac.

Could you check if you have some setting in your /etc/resolver for dev TLD, or if you are using some service like dnsmasq which is trying to resolve .dev to a non-existent location.