I have checked and IF you’ve done business with them, it’s not spam if you send them messages.
I also guess people reporting you has to do with how the previous interaction went, and how many messages you send.
My gut also says it still makes sense to be appropriate with any message you send and only send every couple months or so.
If people are smart about it, they also say something like "I contact previous clients occasionally, if you never want to be contacted, just send me a “Stop” message and I won’t contact you.
As long as you’re respectful AND you did something with them, it makes sense to me, especially people who did something with you when you were new, and if you’ve grown substantially, some of those people are ripe for a reminder that you still exist.
(So many people get started on Fiverr, then six months later are not around for a variety of reasons.)