Inoreader on Twitter:

Due to issues in our secondary data center, you might experience issues with some functionality like search, newsletter subscriptions and accessing very old articles. Our engineers are working on restoring all services as fast as possible. We apologize for the issue.

In a follow-up tweet:

Some details: We've had 3 major power surges today (so far). The first one caused our UPS to fail and to get stuck in bypass mode. A 140+ TB ceph storage cluster is still repairing with multiple failed HDDs after 3 consecutive power failures. This takes time...

In another follow-up tweet:

... No data loss is expected since we also have offline tape backups of everything, but it could take some time to restore articles archive prior to 2019. The other service that is currently affected is the newsletter subscriptions since our email provider is also in this DC.

I recommend checking @Inoreader on Twitter for updates.