Thank you for quick response!
It is now version wkhtmltopdf 0.12.3 (with patched qt)
bench update does not update wkhtmltopdf, pip install wkhtmltopdf says permission denied, even with --user frappe
This works on debian stretch/buster, so should be OK on ubuntu too
#6) wkhtmltopdf - the default apt-get version is outdated. Install pre-reqs, and then a manual/latest version
sudo apt install -y xfonts-75dpi fontconfig libxrender1 xfonts-base
wget https://github.com/wkhtmltopdf/wkhtmltopdf/releases/download/0.12.5/wkhtmltox_0.12.5-1.stretch_amd64.deb
sudo dpkg --install wkhtmltox_0.12.5-1.stretch_amd64.deb