Created attachment 220026 [details] vim version info and order of processed config files The order of processing the config files seems to be odd, as /usr/local/share/vim/vim82/defaults.vim overrides /usr/local/etc/vim/vimrc . In practice, setting "mouse=r" in /usr/local/etc/vimrc doesn't have any effect, as the mouse option gets overriden in the defaults file.
This problem probably lead to the unanswered question at https://forums.freebsd.org/threads/global-configuration-for-vim.60321/ So either the documentation is incorrect or incomplete: /usr/local/etc/vim/vimrc System wide Vim initializations. "... which is overriden by settings in ..." or the order should be different.
I think this is more of an upstream problem than a FreeBSD problem. We don't alter the load order in any way, so (as you mentioned) either the load order or the documentation about it is wrong. Either way, this seems like a problem that needs to get fixed upstream. Vim bugs are filed at https://github.com/vim/vim/issues Can you report there?