Just my 2c, but those gaps look too uneven to be produced by a framework. They remind me of my own html from scratch when I didn’t use a formatter or linter haha
eg:
<html>
{{ if eq .FOO "bar" }}
<some tags here>
{{ end }}
<other stuff>
{{ if eq .BAZ "bim" }}
<some tags here>
{{ end }}
</html>
Especially it looks like they have lots of edits where they add blank lines and then another tag, and then remove the new tag but not the blank line. E.g. https://github.com/thstsa/spacetourism/commit/6411ce05009cc6...
Or sometimes just replacing things they intend to outright remove with blank lines.
With multiple committers, it seems unlikely they're all templating and then checking in the output of the template engine.
{{- [...] -}}
{{ [...] | [n]indent X }}