Opening any page on the website with Safari, I am greeted by this error that stops execution of javascript for the whole page (which includes disabling menu navigation, etc.).

The error is as follows: "Invalid regular expression: invalid group specifier name".

A quick google search yields the suspicion that Safari does not support negative lookbehinds in regexps until version 16.4 from March this year.
https://caniuse.com/js-regexp-lookbehind

The only new regexp with a negative lookbehind is the following from the stringToHTMLWithLinks method: https://github.com/metabrainz/bookbrainz-site/blob/ef17953e6ca8932a9a2e2efd29e50858d89e096f/src/client/helpers/utils.tsx#L180

The Safari debugger doesn't allow me any kind of precision, so that's all the info i have for now, but I'm happy to help test and debug if you don't have access to Safari