I'm not familiar with DNSSEC. What sis the impact of this? Do web pages fail to load or is it just some security warning? Also was this just someone failing to update a cert in time or is this some sort of hack?
If you're using DNSSEC-validating resolver servers (many of the popular ones are), then presumably all the signed names in .RU fell off the Internet completely, as if they never existed, for the duration of the outage.
Either someone failing to update the cert or the person who did it until has been sent to the meatgrinder. I really do wonder what effect war will have on the Russian IT industry. From what I read most IT professionals are protected from mobilisation, but on the other hand they might have a more open view of the world then Putin's regime.
As user, I am unable to visit any pages on .ru domains, as their IP would not resolve.
Reason is highly likely mistake (human side) in signing procedure, not something time- or hack- related.
Someone is most likely CC for TLD RU, aka АНО КЦНДСИ, official registry of .ru TLD.