Why does People's Republic of China (PRC) tolerate the existence of a "de facto embassy" of the Republic of China (ROC) in Russia?

Question

It is well known that Communist China (PRC) is really sensitive about countries that establish formal relations with the Republic of China in Taiwan (ROC).

One prominent example is the PRC reaction on establishing the Lithuania-Taiwan office. (here and below highlight in quotations mine)

The relationship between Vilnius and Beijing has been on the brink since November 2021, when Lithuania allowed Taiwan to open its de facto embassy in the country, making Beijing block exports from Lithuania and slap sanctions on Lithuanian officials. — Deutsche Welle

At the same time, there is a "de facto embassy" of ROC in Russia: "Representative Office in Moscow for the Taipei-Moscow Economic and Cultural Coordination Commission" — Official site

The Wikipedia has this to say:

The Representative Office in Moscow for the Taipei-Moscow Economic and Cultural Coordination Commission represents the interests of Taiwan in Russia, functioning as a de facto embassy in the absence of diplomatic relations. — Wikipedia

[…] the Moscow-Taipei Coordination Commission on Economic and Cultural Cooperation is considered as a formal foreign office — Wikipedia

Moreover, this very institution acts as a hub for consular services for citizens of other countries that have not established such offices with ROC, expanding the consular jurisdiction to a good dozen of countries of the region.
Up until 24 February 2022, even citizens of Ukraine had to travel to Moscow to obtain Taiwan visa. (ask me how I know)

Question: Given that the office in Russia, which is not only a "de facto embassy", but has acted as a hub for strengthening the relationship between European states and Taiwan, why does the PRC apparently tolerate it, while at the same time getting particularly furious on other countries' similar institutions that "harm" PRC dominance even less?

Answer 1

Most countries in the world, including Russia, India, the US and Brazil - all have had a Taiwanese Representative Office for a considerable period - since long before China became a great power.
These are known by the name of Taipei rather than Taiwan:

The Representative Office in Moscow for the Taipei-Moscow Economic and Cultural Coordination Commission represents the interests of Taiwan in Russia - wikipedia.

These countries haven't changed their status quo regarding RoC-PRC situation anytime recently. Even in the Olympics (even at Beijing), Taiwan has been participating as Chinese Taipei. Thus, these countries haven't provoked China as such.

OTOH Lithuania appears to have changed the status quo - they didn't have a Taiwanese representative office in the first place. Plus, this was also in the backdrop of Lithuania dropping out from the 17+1 forum for China-Eastern Europe co-operation.

Also, the Taiwan office in Lithuania carried the name of "Taiwan" rather than Taipei. As per the guardian:

Lithuania revealed in July it had agreed to let self-ruled Taiwan open a representative office using its name, the island’s first new diplomatic outpost in Europe in 18 years. ... Other Taiwan offices in Europe and the United States use the name of the city Taipei, avoiding a reference to the island itself, which China claims as its own territory.

This was clearly meant as a signal to Beijing - who appeared to have received the signal and responded to it using harsh measures.

Lithuania then tried to make some amends when it opened its office in Taipei. As per the Taipei Times:

The new Lithuanian trade office carries the name Taipei, which might avoid a harsher reaction from Beijing.

Answer 2

Amazingly there's a whole Wikipedia entry on this

The breakdown could be summed up as

• The office was established in 1993, which would be shortly after the fall of the Soviet Union

• Russia has never acknowledged Taiwan as an independent nation

• Taiwan is a decent consumer of Russian goods

  In 2005, the total amount of the trade between the two countries (in US dollars) was 2,188,944,473. As can be seen from the data, Russia keeps a positive balance in its trade relations with Taiwan thanks to crude oil, cast iron and steel, nonferrous metals, petrochemical products, ferro-alloys, coking coal, timber, and chemical fertilizers. Russia imports mostly electronics and electronic parts, computers and computer parts, and home appliances.

• China, at least for now, wants to maintain a good relationship with Russia

  China is considering sending weapons, ammunition and drones to Russia, according to information the Biden administration declassified at the end of February 2023.

The TL;DR here is that the office appears to be solely for economic reasons, and not diplomatic ones. China tolerates it as long as Russia is friendly with Taiwan (which may be coming to an end)