[actualwitch]

Google probably tracks all clicks on links in mail. It is easy to see that unsubscribe was clicked, and then more mail that you mark as spam came.

[mook]

That's the thing — it's my bank and it does have transactional mail too. I don't expect Google to be able to tell between those.

It's nudging me towards switching banks.

[actualwitch]

I don't use google mail much, but fastmail seems to be capable of making fine-grained judgements on transactional/promotional mail coming from the same address. I reckon google will be able to do it too, certainly easier than changing banks.