I had found this article about a month ago and these backdoor threats haven’t gone away.
The newly discovered FM11RF08S backdoor could enable an attacker to compromise all user-defined keys by simply accessing the card for a few minutes, Teuwen said. Customers should be aware that RFID cards based on FM11RF08 and FM11RF08S chips are also used outside the Chinese market, with numerous hotels in the US, Europe, and India employing this significantly insecure technology.
I think a lot of companies are leaving China anyway due to rising labor costs. Low labor is why they went there in the first place. If you add rising transporation cost I’d expect manufacturing to return the U.S. The U.S. also has an aging labor bell curve, so Mexico will get much of the work with its shorter supply chain.
Geopolitical events are in the short term scheme of things but they may add impetus to quicken the above.
Seems worthy of a topic in its own right.
Calling it a “backdoor” leaves open the question as to whether this is some kind of testing or diagnostic capability that was genuinely inadvertently left in or whether it is intentional. However there may be no way to answer that question.
For context, here are the relevant specifications and comparison of Mifare classic (old “basic cards”) and the newer actually secure cards (that have been available for about a decade): Differences between MIFARE Classic and MIFARE DESFire cards? - RFID Knowledge - Proud Tek Co.,Ltd Places not only still using the old cards but still getting them for new buildings… 
If I understood from a couple of articles, the big part of the problem are the masses of cheap bootleg/non-original-manufacturer cards that have been available globally. Were they sold or bought knowing they were not from reputable sources (price as the only issue) or were they represented as genuine? Could be both, misrepresentation and greed - blame on both ends.
But, if I’m not mistaken, most readers should be able to use the more secure cards, so it’s not a fatal problem - changing cards is not an uncommon operation. Although, there have been mentions of shortages of the more secure cards. Btw. “cards” may be misleading as those can come in many form factors, not just the “creditcard” size.
[edit to add: If anyone has a Flipper Zero, this may be something to test]
PS In this case, we could be talking about a literal backdoor. 
Not really phone related, but if you are concerned about RFID you could use a RFID jammer in credit card size (Vaultskin - Vaultcard).
Or use Purism x SLNT Faraday sleeves:
The concern is that the underlying device has a backdoor. Jamming the RFID does not solve the problem at all since, for example, if you want to get in to your place of employment, you are going to have to put your card near the RFID reader and let the reader read. The concern is that the reader has a backdoor so that, as a building security measure, it is defective - and unauthorised parties may be able to get in. (That is not to say that building security is the only application.)