TL;DR: The only newsworthy vulnerability is the breaking TEA1 - which is anyways the least secure of them all and only intended for commercial use (that is, no emergency services).
It's kind of like saying...
Vendor: "We support up to 1 zillion bit encryption!"
User: "What's the default out of the box?"
Vendor: "10 bit"
This is IMHO a very unfair TLDR; . The news is that the researchers claim that there is deliberate backdoor, which ETSI denies. If it is true, there cannot be any further trust in other proprietary parts as well.
Which alone implies that the Tetra crypto security theatre is well known in that industry, and isn't a surprise to vendors in the slightest.
The lack of any large allocation for this kind of radio is a big part of why US first responders are stuck with P.25, which is narrowband FM. If there were a wide-enough band in which it could be used, a lot of first responders would have bought TETRA radios a long time ago. P.25 is easy to jam by brute-force power output, and trivial if you directly attack the error correction bits. TETRA and FHSS have a much much larger ratio of attacker transmit power to victim transmit power.
https://en.wikipedia.org/wiki/Project_25#Jamming_vulnerabili...
(FWIW, P.25 is an even worse dumpster-fire than TETRA...)
https://www.powertrunk.com/pressroom/tetra-in-north-america/
That's cool, but it's going to be a niche use at those power levels. One of the things that make TETRA and P.25 so attractive is that you can put a huge, high-power repeater on a hill or tall building and cover a big chunk of a city using (fairly) small low-power handsets. Then multiple agencies (police, fire, spooks, clowns) can all use that repeater and share the cost burden.
The power-limited version looks like it'll always be a fairly niche single-agency-in-single-jurisdiction use. So the threat, while technically not zero, is not at the five-alarm-fire level that it is in Europe.
Edit: also looks like MTA bought their own spectrum license just for this one use:
MTA owns licenses in 700 MHz and 800 MHzEverybody plays the espionage game, Europe really is no exception, they just like to use the US to keep their hands (mostly) clean.