WHOIS says:
Domain name: lobste.rs
Domain status: Expired https://www.rnids.rs/en/domain-name-status-codes#Expired
Registration date: 13.12.2011 10:00:16
Modification date: 12.11.2022 10:42:54
Expiration date: 13.12.2023 10:00:16
Confirmed: 13.12.2011 10:00:16
Registrar: CRI DOMAINS
Does anyone have more details?
edit: he's on it
edit: https://lobste.rs/s/plhit5/lobste_rs_domain_renewal_outage
CRI Domains itself says it can't be registered, but every other registrar I checked will let you proceed to checkout.