I tried to search "odds tracker" on Google and tons of websites offer this service. Not sure if any of them are legit tho, do you have any experience with them? What about building a script to track odds on popular websites, or hiring somebody to do that? It won't guarantee that any match is fixed, but that should not be a problem since no one knows them unless you are an insider.

Not sure why you mention Telegram specifically, since many bots or groups related to services like this are scams. Even if you found a secret/private channel, there's no guarantee they don't share fake info too. At best you can build a bot to track odds as I mentioned above and use Telegram to monitor it. CMIIW.