Hello, is it possible to read messages from supergroups/megagroups (i.e.

with ID starting: -100...) by bot (@xxxxxxxx_bot)?

Solutions with getUpdates or webhook didn't work.
Bot don't see the updates from supergroups with ID starting with -100... .
Even bot's pending_update_count retrieved by getWebhookInfo doesn't increment after messages on supergroups.

Is it technically possible for supergroups/megagroups?

Check /setprivacy settings in @BotFather

Privacy is disabled of course (before adding to supergroup).

Then you should be able to see updates coming from everyone (except other bots)

Yes, bot see updates from other users and from chats also (groups without ID -100...), but not from groups started from -100... (supergroup/megagroup). Was tested on two different supergroups.

Does it say that it has access to messages on the members list?

Is it an admin? Can't remember now if it's necessary for supergroups or not :(

Yes, it has admin privilleges. When adding to supergroup telegram asked to admin privilleges for bot. I mean it is only way to add to supergroups (it is possible with "admin" only).

No, it's crypto.