I now understand, phoenix wallet dont manage scid aliases cause it never start a channel, acinq node running eclair does everytime. And eclair support scid aliases, so it is eclair that gives the alias to phoenix wallet (?)
The research continues...
Discussion
https://www.youtube.com/watch?v=SjLPbjs9LkI
at 6:30 t-bast, cto of acinq, says that they implemented scid aliases. He means in phoenix? I think so. If he would answer my github issue I would be sure.
The scid shiws in my phoenix is clearly an alias, so I'm sure, just want to be sure...