It was revoked before he left China. https://apnews.com/general-news-587786e6e63b4dc2b70c471606d7f584

That didn't stop China from ignoring his asylum request following his release of documentation of hacked Chinese systems and kicking him out of the country because whether you have a valid passport doesn't matter for geopolitical issues. https://www.scmp.com/news/hong-kong/article/1259508/edward-snowden-us-government-has-been-hacking-hong-kong-and-china

Russia was under no obligation to keep Snowden instead of letting him continue to Ecuador. Putin just wanted to use him as a bargaining chip with the U.S., but the U.S. understood that all his documents were already public, so Putin hasn't been able to play that card well yet.