ESET reports the app went undetected in the Google Play store for a year:

The malicious Signal Plus Messenger app was initially uploaded to Google Play on July 7th, 2022, and it managed to get installed more than a hundred times. […] Based on code similarities, we can assign Signal Plus Messenger and FlyGram to the BadBazaar malware family, which has been previously used against Uyghurs and other Turkic ethnic minorities outside of China.