It seems that Kommersant has received the reply from Mozilla, but not the extension developers.
“After recent regulatory changes in Russia, we began to receive persistent requests from Roskomnadzor demanding that we remove five extensions from the Mozilla extension store. After careful consideration, we have temporarily limited their availability in Russia. Realizing the consequences of these actions, we are carefully considering further steps, taking our local community into account,” Mozilla told Kommersant.
I’ve asked the reason in AMO Matrix chat room, no reply yet.