To work around this issue, you can press ESC on your keyboard to close the chat after you are done, or minimize the Telegram window. This will prevent incoming chat messages from being read.
Note
This behavior only occurs if the Telegram window is both visible and unfocused. If the window is overlapped by another application, messages will remain unread.
Steps to reproduce
Open a Telegram Desktop window.
Open any chat.
Place Telegram Desktop side-by-side to a different window (or any other situation in which the Telegram window is not overlapped by another window)
Unfocus the Telegram window, by e.g. focusing another app or the desktop.
Current result
Incoming messages are immediately marked as read. This happens even if the computer is locked. This is problematic since messages can be read even if the user is away from their PC, and they will not be notified on mobile due to this.
Previously, Telegram also detected if the user might have been away, e.g. if there has been no input for a long time, and would stop marking messages as read. This no longer happens.
Expected result
Incoming messages should remain unread until the window is focused, even if it is technically visible.
Same, experiencing this over the last few days. Using macOS and iOS versions.
E
Eugene
Some messages marks as read and I don't see any notification on all devices when I use Telegram client 9.0.1 on macOS 12.6, however replacing client to Telegram Lite 4.2.4 on laptop make it stable again
Dmitrii Systerov
Happens for me as well. Telegram Desktop build 9.0.1.237033 AppStore.