who broke safebooru?

Is there a way to fix safebooru to revert to the old filtering system?

No. If you want rating:s images you'll have to disable safe mode. You can use is:sfw to find both rating:g and rating:s images, and it doesn't count against your tag limit.

is there a way to automatically use the is:sfw tag in every search, or does it need to be added manually every time?

[deleted]

I added
rating:explicit
rating:questionable
to a blacklist, but it's still an issue that safebooru got severely crippled as it is. I can't recommend the webpage to another illustrators as it is right now.