Git uses pager when you run git diff, git show, git grep etc.
If you want to see the result without pager, just add --no-pager or -P.
$ git --no-pager diff
diff --git a/Gemfile b/Gemfile
index b413366f..9d9b8837 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,5 @@
+# This is test diff
+
source 'https://rubygems.org'
gem 'jekyll', '~> 4.2'
$ git -P grep Toshimaru
_config.yml:title: "Toshimaru's Blog"
_layouts/default.html: <link type="application/atom+xml" rel="alternate" href="https://blog.toshima.ru/feed/by_tag/Using git without pager.xml" title="Tag: Using git without pager - Toshimaru's Blog" />
_layouts/default.html: © Toshimaru
...snip...
Reference
How do I prevent ‘git diff’ from using a pager? - Stack Overflow