There is some discussion of this going on here, chatgpt seems to have a contrary opinion but it is so easy to get it to say what you want by misframing the question.
I don’t know what else I can add to that. Receiving gift card for a service you provided to a business is considered income in many places. Especially because gift cards (under the conditions given by Bambu) are considered cash equivalent in many places. And that’s all I can say, I can impossibly speak for every country here.
Of course ChatGPT doesn’t replace a tax advisor, but for a brief overview: ChatGPT - Taxability of Reward Points
I believe OP could be german (just like me), so I wanted …