A feature team, as I see it, is a team consisting of all the people needed to accomplish a released specific feature. So on such a team you might have an architect, a DBA, a coder, a UI guy, a frontend guy etc..

In that case it's important to notice that a team consisting of different specialists is also a team with a very bad bus factor.  The team can stop being productive as soon as even one person on the team gets sick for a couple of days. Knowledge is not shared.

That's why, in the learning phase, it's important to have a goal to turn feature teams into just "teams" of people who work together, each with the minimal skills to do the work of the others. It takes a lot of time, but growing people, taking them out of their comfort zone, and teaching them new skills, is part of your job as a team leader.

As a team leader, you should view feature teams of different specialists as something to grow out of. To be left with only teams of people who can self organize and do the work and have the skills needed to overcome problems such as a person on the team missing. Most organizations don't even have feature teams yet, but as a leader, your vision should strive to have "feature teams" be just a mid-point on the way to teams that share knowledge.