It's not as effective because the app either needs to check 200 or so NIP-05 on start up or it has to check during rendering, creating "now you see the post, now you don't" issue.
But disabling downloads from damus and nostr.mom on your General Relay list seems to reduce most if not all of it.
For instance, I haven't seen a spammer or impersonator today.
The one where you replied with the transparent background of Amy got absolutely smacked π
Thought I cleaned my relays enough but alas.
It's not just you. I barely see any, ever. Somebody mentioned 90% spam in replies and I had no idea it was that bad. It's only really a couple of big relays now that are letting it through.