Mobile subscriptions are a convenient way to pay online. To make a payment, you simply follow a link to your mobile service provider's page and tap a button to confirm. Unscrupulous content providers can exploit this convenience to fraudulently sign you up for paid services.
Mobile subscription pages are published on the sites of mobile service providers, but the page content is created by third-party content providers. Some of them deliberately conceal information about payment for the service. For example, the payment button might be labeled View or Continue. If you tap a button like this just once without reading the terms at the bottom of the page, you may find that an amount of money is being deducted from your mobile account on a daily basis.
Yandex.Browser will display a warning if you open the page of a mobile operator that has a mobile subscription. Tap Proceed to payment only if you really intend to pay for a subscription.