The other dev chiming in at the end with "I've heard only good things about Alacritty's default colorscheme so far" was also frustrating. Saying "well nobody else complained" is an awful reason to dismiss an issue.

Considering this is their reaction to someone pointing out that their green is actually yellow, I'm not surprised that they are in an echo chamber.

Echo chamber is one term, another would be tribe.

An insecure group member feels threatened by an outsider and lashes out. Another group member sees an outsider triggering a group member and he immediately jumps into help. Together, they attack the outsider and drive him off.

I think if the maintainer was less insecure and more able to take critique, the exchange wouldn't have aroused the "fight or flight" instincts of the group.

An open source project with a closed source mentality.