This is probably just Ukraine trying to discord among Russians, but anyway:
Now seriously. FSB/PMC try to eliminate leadership of Defense Ministry/GHQ. Before personnel change, FSB is in knockdown — missed Putin's bridge explosion. Defense Ministry can now blame FSB for the future South loss. Isn’t it obvious who made an explosion? Truck arrived from RF.
— Михайло Подоляк (@Podolyak_M) October 8, 2022
That is, an advisor of Zelenskyy is suggesting the Russians did this themselves, basically due to a power struggle. Again, Ukraine doesn't seem to shy away from sowing discord, so I fully expect Ukraine to be behind this, but 'Russians did this' is definitely one take on this too...