Gold automatically converts to game pass?

your gold subscription was automatically converted to Game Pass core,

If game pass ultimate is purchased, ANY gold is automatically converted to game pass,so I dont think its residual gold sub

If an Xbox Game Pass Ultimate is active, when you redeem a code for Xbox Live Gold or Game Pass for Console it will automatically be converted. In the future, it would be best to make sure that the Xbox Game Pass Ultimate is not active so it will not be converted.

I had xbox gold does that automatically change to game pass core?

Yes, Gold became Core.

Any old Xbox Live Gold cards bought and redeemed now are also automatically converted to Core.

Do you have a standard Game Pass or Game Pass Ultimate? Since Ultimate include Gold it automatically converts standard Gold or Game Pass into Ultimate as well when you add it. If you added the gold card before purchasing Ultimate, it would have converted
at a ratio of 1:1. If you add Gold after purchasing Ultimate it converts at a different rate and would have added 4 months of Ultimate instead of 12 months of Gold. You can view the chart in the Game
Pass FAQ.