Twenty-two of Russia’s 30 most popular Android apps monitor whether users have a VPN service enabled, according to research by RKS Global. The Russian business news outlet The Bell first reported on the study (.pdf) on April 10.

Banking apps are the most common trackers: T-Bank, Sberbank, VTB, and Alfa-Bank all conduct such checks, as do Yandex and VK apps including Yandex Browser, Yandex Maps, VKontakte, and Odnoklassniki.

Among marketplaces, Wildberries, Ozon, MegaMarket, and Samokat are on the list, along with Avito, 2GIS, and the state-backed messaging app Max.

Apps that do not detect VPN usage include Yandex Market, Yandex Food, Gosuslugi, Yandex Go, Dzen, Mail.ru Mail, MegaFon, and Mir Pay.

Eighteen of the 30 apps studied send VPN status data to their own servers, and 24 of the 30 transmit a list of installed apps to the server, the researchers found. “If Sberbank is sitting next to a VPN client, the developers and security services know about it,” the researchers said.

Yandex Browser was the only app among the 30 to search a device for the Tor anonymity browser, the RKS Global report found. Samokat and MegaMarket retrieve a full list of all VPN apps installed on the device.

As part of its crackdown on VPN use, Russia’s Digital Development Ministry demanded that major internet platforms restrict access to their services for users with VPN enabled by April 15.