Who can see my responses to a Workplace bot?
When you message a bot, you're messaging an application built by someone in your organization or built by a third party.
The developers of that application will have access to the conversation between you and the bot. When you add a bot to a group chat, the developers of the application will have access to the whole group chat thread - just as any person would if you added them to the group chat.
Keep in mind that as with all your content on Workplace, your Workplace admin may be able to see the content you post, or messages you send or receive — this includes messages you exchange with a bot.