I switched to only paid relays and haven’t seen any since
Discussion
Some of us are planning on deploying small personal relays. In that circumstance, we are on the hook for moderating our own spam.
I didn't mention NIP-56 kind 1984 reports. But subscribing to those and treating them judiciously can also help.
I think small relays are the right way to go. micro relays, micro apps. everyone will be happy.