Security issues? Security compromises? No.
That’s a Safari experimental features setting used for adding or removing prototype or potentially problematic features for specific websites from within the browser, and the word hack in that context means a kludge or ugliness or an expedient mechanism, and not an issue with security. Experimental features allow a way for browser developers and for specific websites to enable or disable specific newer (incoming) or older (outgoing) features of Safari. In this case, related to Passkey support.
If security is of interest, start here: Personal Safety User Guide - Apple Support