CatherineEleen - great clarifying questions.
Does it mean that now you can give access to team members to a private channel of a team but not the other channels of the team?
Not exactly. Private Channel members MUST be members of the Team, as you are experiencing, so they will have access to all non-Private Channels, and any Private Channels where access has been granted. That said, they will only have access to Private Channels to which you give them access. Let's say your Team and channels look like this:
- OIG Investigations (Private Team)
- Team Q&A (public channel)
- Resourcing Help (public channel)
- Investigation: John Doe (private channel)
- Investigation: Mike Smith (private channel)
If I am a member of your team and you grant me access to the Mike Smith investigation channel, but not the John Doe channel, I will have access to both public channels and the Mike Smith channel. I will not see that the John Doe channel exists, nor will I have access to it.
So the Private Channel is a sub-membership AND only visible to members of the channel. Owners of the team will see that the channel exists, but not have access.
Now, if you're looking for a channel that has membership outside of the Team, the shared channels feature, also called Teams Connect, should help. I don't see it on the roadmap right now, but this is a blog post about the future feature: How Microsoft Teams Connect (a.k.a. Shared Channels) Will Allow Collaboration Without Borders (avepoint.com)
Let me know if I cleared this up!