invalid byte sequence in UTF-8?

[Dopp-Tanner]

vendor/bundle/ruby/3.3.0/gems/rspec_junit_formatter-0.6.0/lib/rspec_junit_formatter.rb:185:in `sub': invalid byte sequence in UTF-8 (ArgumentError)

string.sub(STRIP_DIFF_COLORS_BLOCK_REGEXP) { |match| match.gsub(STRIP_DIFF_COLORS_CODES_REGEXP, "".freeze) }

Began getting this in our CI Pipeline recently, not exactly sure what could have caused this, happy to provide more context but I'm not really sure what context would be helpful here.