Safe search locked by isp

So today i realised that the safesearch was turned on and locked both on chrome and youtube. I changed the dns to google public and the issue was resolved. However why would this happen. Can certain content cause this issue or is it just a bug. Im not on a public network and there are no parental controls as far as i know

UPDATE: the issue was resolved on its own. Thanks for the help

bug can chrome dns google isp issue locked network privacy public safe search today youtube