>>213755500I would not be so sure, if you look the regions that have had the biggest drop in TFR 2021-2024, out of the top 10, 7 are ethnic republics or regions (Tuva, Nenets, Buryatia, Kalmykia, Altai, Yakutia, Mari El).
You could probably infer the ethnic Russian TFR with the percentage of Russians in each region but I'm too lazy. I think the drop has been concentrated among high-fertility minorities such as Tuvans and Buryats although Chechens do not seem affected. Probably Russians fell a bit less than average