In the company, Market Research is led by the Product team, and they do not always share the results with marketing and/or sales. They implement changes and the customers are not always happy bcs sales did not know and/or knew how to help them. How can I improve this communication?

Ultimately what you're looking for is for a true partnership: to be more in the loop on what product is building, why, and what initial feedback is from early customers -- a closer teammate to the product development lifecycle. To get there, I've found the most success building trust by proactively bringing market insights to the product team so they see you as a value add in their development work. For example: are you hearing customers talk about a new use case? Capture the feedback and data and share with your product counterpart. Are you seeing win rates rise or fall in their product area? Flag this to your PM, and engage in win/loss interviews to unpack what's going on. The more you can be a partner and add value to the relationship, the more they'll bring you in as well.