The output:
wkhtmltopdf test.html test.pdf
Loading pages (1/6)
Warning: Failed to load file:///assets/frappe/css/bootstrap.css (ignore)
Warning: Failed to load file:///assets/frappe/css/font-awesome.css (ignore)
Counting pages (2/6)
Resolving links (4/6)
Loading headers and footers (5/6)
Printing pages (6/6)
I get the same output on the instance without the problem.
Both the.css files are fount in ./frappe-bench/apps/frappe/frappe/public/css/ , on both instances- the one with the problem , and the one without.