Posting my general opinion, site linked only seems to have a couple sentences, so I'm guessing it's designed for JSers.
Jet Brains published this statement.
"Another point of entry may have been a backdoor in software developed by a Czech company called JetBrains, run by Russian nationals, that supplies its software testing product, TeamCity, to 300,000 businesses around the world, one of which is SolarWinds."
The article then moves on and does not mention this again or provide any evidence.
That article attributes the claim to "officials and executives briefed on the inquiry".