A tip for new players for telling official in-game bots (at low rank) apart from players who may or may not be botting is to bring up your friends list (the icon on the top left of the screen). If your opponent’s name does not show up under “recent” then you are playing a legitimate in-game bot and not an actual human player.
Compare between the different screenshots below taken against an in-game bot with ones taken with a human player’s account.
https://imgur.com/a/Vc5tmag
Barcodes accounts are still common in Arena despite the creation of a “barcode jail,” which was an attempt to segregate super-drafters who retire lots of bad drafts while in search of a god-draft that can stomp most other decks. There are workarounds to avoid ending up in barcode jail.