I'm sorry this happened to you and it completely sucks. In my mind, there's absolutely no reason for a reputable professional with years of outstanding delivery to be demoted from TRS to level 0, unless they started running an obvious scam, but even then, they should be removed from the platform in that case, not demoted.
Fiverr doesn't seem to care about quality and professionalism, because if they did, they would promote your gigs instead of unjustifiably punishing their standing (and your profile as a whole).
I have one gig with around 450 reviews, 4.9 rating average. When I research SEO page for my niche, and filter by both "relevance" and "best selling", most gigs shown right at the top are :
1. ads
2. Gigs with barely any reviews or no reviews at all (also, gigs with 4.1-4.8 rating average)
3. Numerous gigs which blatantly copy my gig photos or description word for word, something which I stopped paying attention and taking action against some time ago.
Right now, my gig shows up on the first page, but it keeps regularly cycling between the first and fourth pages for seemingly no reason at all. And it stays on the fourth page for weeks at a time, while the first page is populated with new gigs with no track record at all.
I wouldn't jump to put the blame on yourself, Fiverr algorithms have been notorious for prioritizing low quality and low effort gigs instead of the ones which have a proven track record and trust from buyers. Even if Fiverr values profit above everything else (which it seems that it does), it doesn't make any sense to me.