However, had the author normalized the instances.json with something like "jq -S" then one would end up with a more reasonable 1736 textual changes, which github would have almost certainly rendered
It doesn't help fix GitHub UI views, but you can use the --tool option to git diff and configure alternative diff tools in your git config, including something like piping through a pretty printer or using a (generally much slower) character-based diff tool rather than a line-based one.
As a heads up to anyone trying this stunt, please be mindful that git-diff is ultimately a line oriented action (yeah, yeah, "git stores snapshots")
For example https://github.com/pmc-ss/mastodon-scraping/commit/2a15ce1b2... is all :fu: because git sees basically the "first line" changed
However, had the author normalized the instances.json with something like "jq -S" then one would end up with a more reasonable 1736 textual changes, which github would have almost certainly rendered