Can I use promts at MiJourney and using brand names (fashion / furniture)? And then sell at Adobe?

That's an IP violation. No unauthorized use of protected brand names, trademarks or logos allowed.  That goes for prompts, images, videos, titles, keywords and descriptions.

• https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
• https://helpx.adobe.com/stock/contributor/help/generative-ai-content.html
• Model/Property Releases:
  https://helpx.adobe.com/stock/contributor/help/model-release.html
  https://helpx.adobe.com/stock/contributor/help/property-release.html
  
  

Do you have a question for the community members? Why did you post this image?

No. You would be at risk for Midjourney creating furniture or fashion lifted almost verbatim from the brands in question. Always keep your prompts very generalized and do not refer to any known brands. As you said, "the algoithm works well." But probably too well. The greater the randomization in a prompt, the better. I even use mathematical equations on occasion, with results that range from absolute nonsense to surprisingly unique images. Since Midjourney and other AI apps can create very realistic images of celebraties and politicians, it's logical to assume it can and will do the same with furniture, fashion, cars, etc.

The guidelines are quite clear:

Generative AI Content (adobe.com)

• Don’t submit any work created with prompts referring to or based on people, places, or property unless you have the legal right to do so (e.g., via a model or property release). 

If you refer to designs or designers in your prompts, you are violating this rule.