The packet capture isn't very interesting, but there is one major takeaway.
At a minimum,
we can tell that active mode is being used because a new TCP session sourced
from port 20 is initiated from the server towards the client.
We cannot see the contents of any signaling packet such as extended port,
retrieve, or store commands.
Passive mode is different.
There is no TCP port 20 here,
but instead a new TPC session is formed from client to server,
this time using port 42568.
This is the passive port sent from the server to the client in
response to the extended passive command,
which we cannot see.
To be clear,
the visibility of TCP ports in FTPS like this is not specific to IPv6, but I wanted to refresh it here.