Some networks may take time to update
Overflow pages were being flagged by security filtering built into some home internet services. This has been resolved. Providers refresh this data on their own schedules, so a small number of users may still see an error until their network updates. It will clear on its own.
Anyone still affected can reach Overflow by using cellular data, a different network, or a VPN in the meantime.
No donor or account data was involved at any point, and recurring gifts processed normally throughout.