Online court documentation offers some insight into the launch delays suffered by Bars-M (14F148) nr. 3 and 4 (launched as Kosmos-2556 in May 2022 and Kosmos-2567 in March 2023).
https://sudact.ru/regular/doc/82NKpJry2V5s/https://xn--90afdbaav0bd1afy6eub5d.xn--p1ai/51480327The Progress Rocket and Space Center (RKTs Progress) received a contract for the production of these satellites as well as two others (nrs. 5 and 6) on 27 August 2014. As is mentioned in the first document (dated February 2020), satellites nr. 3 and 4 were originally supposed to be delivered to the Ministry of Defense by late November 2017 and satellites nr. 5 and 6 by late November 2020.
By early 2017 the delivery of spacecraft nr. 3 and 4 had slipped to late 2018 and by early 2019 delivery of spacecraft nr. 3 was expected in late 2019. The only reason given in the document for the delays are problems with the delivery of foreign-built electronic components, among other things for the high-speed data downlink system (designated 14V122), manufactured by NII TP (Scientific Research Institute of Precision Instruments). As is standard practice, these components are not purchased abroad by the prime contractor itself (in this case RKTs Progress), but by a company that acts as a liaison between the foreign supplier and the prime contractor (in this case Setevye Tekhnologii).
The second document (dated July 2020) specifically links the delays to Western sanctions. Although the spacecraft serial numbers as well as many dates were deleted, it is almost certainly about satellites nr. 3 and 4. It literally says:
“Because of the economic sanctions imposed on the Russian Federation by the United States and the European Union, it became impossible to carry out the work within the set timelines since the foreign electronic components were not delivered. The economic sanctions imposed on the Russian Federation were force majeure circumstances that [significantly impacted the ability to carry out] the government contract.”
At the same time, the document says, the need arose to modernize the 14F148 satellite by incorporating new electronic components into some of the on-board equipment, among other things by updating production techniques. Reading between the lines, that should probably be interpreted as meaning that Western-built electronic components had to be replaced by Russian ones and/or those purchased from other foreign suppliers.
That modernization work became the subject of a new goverment contract signed between the Ministry of Defense and RKTs Progress on 5 March 2016 under the code name “Matritsa” (“Matrix”). At the time of writing, the launch of the first satellite adapted under Matritsa was expected in 2021. Its new systems were to undergo at least fourteen months of in-orbit testing, following which changes might have to be made to the next satellite. In the event, the interval between the launches of satellites nr. 3 and 4 was about 10 months, indicating that any such changes must have been minor.
It would seem that the modernized satellites have retained the original military index of Bars-M (14F148). This was not the case for Glonass-K2 and Rodnik, which are also undergoing significant modifications because of the need to replace foreign-built components. Glonass-K2 switched from 14F160 to 14F170 and Rodnik from 14F132 to 14F161.