Durov introduces Telegram’s take on ads in his Russian channel.
The translated channel post (translated with DeepL):
Soon, official advertising messages will appear in Telegram channels for the first time. Most users will hardly notice this change - for three reasons:
Telegram will not show advertising messages in chat lists, private conversations, or groups. The ads will only affect large channels - services where there are already ads and whose support results in the largest expenditures on the part of Telegram.
No personal information will be used to show ads. User privacy is paramount to Telegram. The content of advertising messages will depend only on the topics of the channels in which they are displayed, and not on users’ personal data.
Official Telegram advertising messages will be unobtrusive. Only short texts without external links or photos will be allowed in them. An advertisement may appear only after all new messages in the channel have been viewed.
Ads posted by Telegram channel owners themselves in the form of regular messages are now found in Telegram channels. The official advertising messages that Telegram is introducing will be much more comfortable for users. The income from such advertisements will allow Telegram to continue providing users with a free and unlimited service.
Documentation:
As far as I know, official apps still don’t support sponsored messages, but they’re probably going to support them in the next version, which should be released in a couple of weeks.
This thing has not been publicized by Telegram itself yet - it has been announced just on Durov’s russian personal channel