In my experience, CSAM accounts get flagged many times, channel owners remove the account from their channels, but the account continues to post the material elsewhere.
This wouldn't surprise me in the least. My guess is that Telegram just doesn't put much effort into busting either spam or CSAM. They let channel admins do it.
I suspect that Telegram could put significantly more effort into CSAM suppression and enforcement, but I seriously doubt this is really what's up with the French arrest of Durov.
