I signed up for one of these search services that can trace forgotten bank accounts or old pension schemes, I found nothing but went through the motions as the service was recommended by a TV financial expert.
The day after I did the search my spam emails went from 1 a week to 15-20 a day, I asked the company what was going on and they said that they do not sell data or email addresses but the coincidence seems a bit too much, same email address for 25 years and this spam had just gone nuts. I have gone through all the blocking or deleting ideas that are on gmail but if I had my time again I would have created a secondary and disposable email address.
The biggest success was finding that most of the scammers come from once source. In the From field in Advanced I entered *firebaseapp.com and delete and do not send to spam, 90% of the spam has gone, or at least, not visible.