My current world was created in 1.164, and has been upgraded to 1.17. I have a drowned farm (in old chunks, not that that should matter), and they consistently drop gold ingots (along with everything else, rotten flesh, nautilus shells, tridents, etc). I have yet to see a copper ingot.

The farm is the "lure them with turtle egg towards a nether portal and kill them there" variety. 

I'm killing them with a Looting III netherite sword.

Update: seems to be world specific. I tried it in a new (generated in 1.17) world, creative mode, similar sword, and got copper ingots. I then tried it in an old (created in 1.16 but currently running 1.17) creative testing world (similar sword) and got gold ingots. I then moved to new chunks (even dug a nice hole in tuff to spawn them), and still got gold.