EU is irrelevant for Russia because, for it, the Ukraine conflict is a proxy war between Russia and NATO. That is why it only seriously engages with the western superpowers (USA, UK, France) and the emerging powers (Germany and Turkey) in NATO on Ukraine. It also helps that the European superpowers dictate their will on EU.

> so when is Russia going to demilitarize Kaliningrad, because having a military base so deep in EU is unacceptable?

Russia has been willing to demilitarise Kaliningrad, and only determined not to do so because of NATO's eastward expansion - "We want to demilitarize Kaliningrad, but (we) will have to deploy even more troops there once Poland becomes a member of NATO." - Aleksandr Shokhin (Russian Duma’s First-Deputy Chairman). (It also doesn't help when NATO members claim publicly that unless Kaliningrad is demilitarised, NATO cannot have dominance in that region ( https://www.sb.by/en/poland-demands-demilitarisation-of-kali... ) - that should really convince Putin to hurry up with the demilitarisation! In fact, after Sweden and Finland joined NATO too, Russia has expanded its military presence there greatly too ( https://news.err.ee/1609274853/lithuanian-intelligence-russi... ).