Yes, this is true.
According to the Wall Street Journal, “A Moscow court on Tuesday upheld the detention of Wall Street Journal reporter Evan Gershkovich, who was arrested while on a reporting trip last month and held on an allegation of espionage that the Journal and the U.S. government vehemently deny.” The article goes further on to say it’s rare for people to win appeals in cases like this there, it was held behind closed doors and he is being held in pretrial detention. He has pleaded not guilty to the spying charges. The Wall Street Journal’s parent company tried to also pay a bail to get him put on house arrest, but that was denied as well.
https://www.wsj.com/articles/moscow-court-to-hear-appeal-on-detention-of-jailed-wsj-reporter-evan-gershkovich-9c464c6c
The New York Times reported the same saying, “The judge, as expected, denied Mr. Gershkovich's appeal to lift his pretrial detention, leaving him in Russian custody. He was ordered back to Moscow's Lefortovo prison, one of the most infamous detention centers in Russia, where inmates are held in isolation with only rare visits by lawyers.”
https://www.nytimes.com/2023/04/18/world/europe/wsj-reporter-evan-gershkovich-moscow-court-detention.html#:~:text=The%20judge%2C%20as%20expected%2C%20denied,only%20rare%20visits%20by%20lawyers.