when i downloading that i found a user which ip is display as 2001:bc8:32d7:12c::51413 and region displayed with unknown.the actually addr is 2001:bc8:32d7:12c::with port 51413 and correctly display is 2001:bc8:32d7:12c:::51413.Is this a display bug?

It sort of is but isn't. The way Tixati displays IPv6 addresses is without the brackets [ ]. So if the IPv6 address ends in "::" like the one you said then there will be another colon after it for the port number.

The address fd21:ab5:93e:223a:: with the port number 7892 would show up as fd21:ab5:93e:223a:::7892 in Tixati.