Safebrowse.io is blocking sites on my iPad in all browsers

I can’t access a trusted website on my iPad or my phone. When I try to open the site, I get a message from Safebrowse.io that the site is unsafe, and clicking the option to proceed anyway doesn’t get me through the blocker. The same thing happens on wifi or cellular, in Firefox and in Safari both.

I have checked for extensions under Settings for both Firefox and Safari and don’t see anything that might be relevant. Existing answers that I’ve found to this problem seem to begin with entering info via Finder, which I don’t think we have on the iPad/iPhone.

I can get to the blocked site if I enable a VPN first, but that’s a bit of a pain and it slows down the data.

No idea how ‘safebrowse’ got on my system or how to get rid of it. Any advice would be welcome!