We received two emails on OTRS a few days apart from readers who could no longer access Wikipedia using old versions of Safari.
It wouldn't have surprised me to find a bug on phab indicating that support is no longer maintained for these old versions, but I didn't find anything.
Also, they are still indicated as maintained on https://www.mediawiki.org/wiki/Compatibility#Browser_support_matrix.
– Safari (5.1.10) (6534.59.10) / Mac OS 10.6.8
– Safari (?) / Mac OS X 10.5.8
Is it a bug or is it wanted ?