After searching around for a while I found this thread. Translated using google and ran everything. At some point, php7.3 was updated to 7.4, breaking the pihole dashboard. I can only assume it was when I updated my dietpi vm.
I did have to reinstall the packages that were removed, including:
php7.3-cgi php7.3-cli php7.3-common php7.3-curl php7.3-fpm php7.3-gd php7.3-intl php7.3-json php7.3-mbstring php7.3-opcache php7.3-readline php7.3-sqlite3 php7.3-sqlite3-dbgsym php7.3-xml php7.3-zip
Thanks for everyone's help on this!