No, just personal experience (I use telegram for many years) and absence of server data implications anywhere across the issues in the past (at this time too). You can find questionable or illegal businesses in telegram with a few words, they are all public channels. Hence “no moderation” accuses mentioned in every article.
There are of course darknet-like private communities, but I assume they are not a subject of interest at this time. Authorities would need to dig very deep past all the obvious illegal stuff, and telegram shouldn’t care about resources consumed by such a small chunk of user base. Those groups will stay, as they are, private and safe, I assume, for quite some time.
I mean the basic logic of the service was designed somewhere before its release. Data policies, promises to users are nothing if you assume services should adapt to stuff like this, at the expense of breaking those policies and promises.
Here is an old article from telegram about reasons for how it works https://telegra.ph/Why-Isnt-Telegram-End-to-End-Encrypted-by-Default-08-14