Why is the handler for adding a user in the chat not responding?

Question

Python

Hello everyone, tell me someone faced such a problem, there is a chat bot for tg aiogram, which catches new users who have joined the chat, it worked fine for a year and then for some reason it stopped seeing the content_types=['new_chat_members'] event in the main chat , on the entry, adding the user does not react at all. The bot is the admin in the chat.
But if I add it to any other chat, then everything works fine, what could be the problem?

And another interesting thing I noticed is that if I add a random bot to the main chat, then the event comes, but does not react to people