There is a senior developer in my scrum team. Let us call him Jack.

Jack is with this team since the beginning. The team has 8 people including Jack me and the PO (I am the scrum master of the team). Jack knows inside out of the product that we are building. He has very good coding skills and he is a very good architect as well. Usually whenever there is a discussion about a difficult problem, we have one stop solution provider – Jack
Once our team had to come up with a solution for a very difficult problem. The problem was faced by the customers since quiet sometime and now it became very urgent to solve the problem because otherwise we might even start losing our customers.
So we gathered in a discussion room and started discussing the problem and probable solutions. Jack was very prompt in asking the required questions to the PO. He was leading the discussion to understand the issues. During the discussion while the team was still busy trying to grasp the issues and the pain points of the customer, Jack came up with an easy and good solution. He explained the solution to the team. The team got the idea what they had to do. So all of them went back, they did what was decided by Jack and delivered the solution to the customers. The customers were happy with the solution and so was everyone else.
Now do you see a problem in this small story?
If not , you can try to connect it to your own teams. Almost all of us has a Jack in our teams. Try to talk to your team members and ask if they see any issue.
It is good that the team was able to provide a solution to the customer and they were able to make everyone happy. But in this approach of working, what we did is, we silenced the other 4-5 team members of the team. We did not give them the space to think and come up with the probable solutions. Because those 4-5 team members already knows that someone in the team always has the answer.
So while Jack is having his best intention to help the team and the customers with an easy and good solution in a short span of time, he is ignorant of the fact that the rest of the team is shutting themselves down since he is always the only one speaking.
If this continues in almost all the discussion and for all the issues then eventually Jack will become the institutional bottleneck. Every problem statement will come to Jack and there will not be much progress in a work until and unless Jack is involved in it. Because that is what the team will be used to. On the other side Jack will be so much overloaded carrying the burden of the full team’s performance that with each passing day he will become lesser efficient.
This is the point when you as a Scrum Master need to recognise the issue and hold a mirror for Jack to make him see that even if he is doing all the right things and for the right reasons, he needs to take a step back. Because what Jack is doing is giving everyone a short term win which is leading to a long term loss. One particular person in a team always answering the questions and always providing solutions for all the problems isn’t the healthy thing from a team’s perspective and also from an organisation’s perspective.
If Jack knows the answers or the solution then he can help the team by empowering his team members to arrive at the right solutions.
How can Jack do it?

You as a Scrum Master need to suggest Jack to hold himself back for sometime and let other team members speak during discussions.
If even after 10-20 seconds of silence in a discussion no one is stepping up then may be Jack needs to look around the room and ask some right questions which will help people in coming up with the right solutions. As long as Jack is the first person to answer the questions, we will not be able to empower our teams.
We need to talk in questions to empower others. We need to guide people towards the solutions instead of giving them the solutions directly. We need to show trust in them by giving them the opportunity to speak up their minds. If we talk in questions then we empower the teams to answer.

In the VUCA (Volatile, Uncertain, Complex and Ambiguous) world we need all team members to be Jack and not have only one member become the Jack of the team. When we have a team full of Jacks then we are on the right track to move towards a High Performing team
P.S. – While writing this blog I came across this Harvard Business Review on Collaborative Overload. The problem of having only 1 team member as Jack is mentioned here as single ‘extra miler‘. You may have a look at the article – https://hbr.org/2016/01/collaborative-overload?utm_source=facebook&utm_medium=social&utm_campaign=hbr&fbclid=IwAR1t-4KsPgmou6vVoOirrq4XyQZGMHUCP6BGavEHo1Oxl1bLEzUJjY0iNoM