The latest security update I believe is 10.14.6 (2020-04)
For what it's worth, I never ever use Safari, and just opened it without an internet connection, to check the current version. It's version 14.0 (141610.1.28.1.9). I see the current default search engine is Google.........
Also in Safari all the AutoFill web forms are selected by default - great if you like that facility, but no way would I ever agree to that, especially for credit cards, passwords and other forms.
Over the years on Macs I've always used FireFox, which is not only regularly updated but also pretty secure with default settings, and is imho the best browser for customizable privacy - these being easily tweaked within Ffox preferences for additional web security.