Ukraine figured out how to slow down Russia, burn their tanks and heavy armored vehicles. Russian repair centers won't fix burnt tanks (BER) beyond economic repair

Russian repair plants refuse to repair military heavy armored vehicles returned from the war in Ukraine. This includes mostly tanks and armored vehicles for the infantry. The reason: much of the equipment is returned with burnt bodies and repair is impossible.

Reports of problems with heavy military equipment and the inability to carry out quality repairs, both in the field and in the repair plants of the Russian Federation, appeared as early as May. Several train sets were then seen transporting obsolete T-62M and T-62МВ tanks into the interior of Ukraine, the tanks being mobilized and taken from the reserve as well as from the inventory of military units in Tajikistan, Libya, and Syria.

https://bulgarianmilitary.com/2022/07/06/burnt-tanks-return-to-russia-repair-plants-refuse-repairs/