As far as I know (I've searched for it on AskUbuntu), it was avoided because of a security hole in Ghostscript up to version 9.24 but UbuntuDDE ships version 9.50, and, in fact, both Debian Bullseye and LMDE 4 allow freely the convertion. I will modify the file /etc/ImageMagick-6/policy.xml, but maybe you could do the same as Debian and Mint, I do not have a Canonical Ubuntu 20.04 to see if they have a regression. Thanks, Aldo :-)
This is strange because I do not have any issue with Chromium on Ubuntu 18.04 or Linux Mint 18.3 Thanks, Aldo :-)