I went from less than 10 messages a year in my spam folder to as many as 60 a day in the past few months. But Gmail continues to keep all of them out of my Inbox. I’ve had my Gmail account since the beta and also have a paid Google Workspace account handling mail for two personal domains. Gmail is forwarded to Google Workspace and a handful of rules sorts and files most of the messages for all three accounts.
If you are already a Gmail user you might want to consider forwarding one of your other accounts to Google to see if a similar set up would work for you.
I’m looking for the same thing, because I’m downsizing from an iMac + MacBook to just a MacBook, so I can’t run SpamSieve all the time. That means I’ll get all kinds of spam on my iPhone. I have two email accounts - gmail and iCloud.
I’ve been looking for something similar as well. Something that will not only help with spam, but also sort mail. I’ve gotten into the “home server” space lately, and given the privacy focus on that community, I’m surprised I haven’t found an open source self-hosted alternative to Sanebox.