I am not defending Telegram, but as a social media application (and a private chat option), Telegram is only complying with existing laws. Copyright materials are a taboo on ANY electronic medium (including the open web). We just had a major issue around the Z-Library. Each time anything of this sort happens, I see the Signal users coming out from no-where. These news aren't a big deal, and numerous public channels have faced the axe. Most of them have changed tactics by going "private" by rapidly changing their invite links or using bot services to "verify users" before they join.
Public groups earlier sharing copyright materials are "banned". There are numerous bots that connect to torrents and upload content to Telegram. Z Library still serves content; Nexus bots have just rolled out a feature to connect your bot (through API token). Signal serves a specific niche of users, and I think polarising arguments (or moralistic stands) are only to play to the gallery.