A: Due to Telegram's restrictions, if too many messages are sent in a short period, the bot will get flood-controlled and have to wait for a certain time. Though the bot will retry, if still gets flood controlled, the message will be dropped. Avoid subscribing to too many feeds, especially in channels and groups (they have a much stricter flood control threshold).
A: Just add the bot to your channel or group and send commands. In a channel, "Post Messages" permission is required. If you are an anonymous administrator of a group, the bot needs to be an administrator too (no permission needed) to verify your identity.
A: Send /lang and select language again. The bot will update your command list.
A: The bot is designed to be asynchronous, so it is lightweight and fast. Even if there are over 6000 feeds, the bot can still run on a single core VPS, with an incredibly low load average (~0.2) and approximate 350MB memory usage. The bot can still work fine in such a condition and its stability and usability will not be influenced. As for the memory leak problem, it is a known issue of an upstream library feedparser, and it is not a bug of the bot.
A: "Muted" notification is not aimed to disable the notifications, but to make the notifications with no sound. Due to the limitation of Telegram, disabling notifications completely on the sender side is not possible.
A: Set the env variable MULTIUSER to 0.
If you need to use the bot in a channel, read the next question.
Using the bot in a group is possible even if you don't have the multi-user mode enabled, as long as you are a non-anonymous administrator of the group. If you are an anonymous administrator of the group, read the next question.
A: Firstly, set the env variable MULTIUSER to 0. This will make guests unable to use the bot.
If you want to allow a certain user to use the bot, send /user_info user_id or /user_info @username to the bot and promote their to "User".
If you want to allow a certain channel/group to use the bot, you should promote both the channel/group itself and at least one of its administrators to "User". Only the promoted administrators can operate the bot in the channel/group.
A: Once the bot finds itself lacking the permission to send messages (not granted or being blocked), it will immediately unsubscribe all subscriptions in this chat. Meanwhile, if this chat is a channel or group and the bot is still a member of it, it will leave the channel/group. Make sure to grant the bot enough permission (sending messages) in channel/group.