@arago44 I'm surprised FlavaWorks can even afford the postage to send you a letter. That firm has been in trouble for years: The civil action mentioned in the link from @geobear40 was dismissed; see https://www.pacermonitor.com/public/case/22240353/John_Doe_v_Flava_Works,_Inc_et_al for a chronology, although you'll need a subscription to read the actual court documents.
More recently, FlavaWorks tried suing Adam4Adam for copyright infringement, claiming that A4A used/uses, without permission, copyrighted FlavaWorks images in advertising third-party products. (Disclaimer: I have a subscription to Adam4Adam, and I see and delete their third-party advertisements. I am not familiar with FlavaWorks' material and have no opinion on the merits of FlavaWorks' claim.)
To make a long story shorter, FlavaWorks apparently lost this action (although I haven't found documentation of that). A4A then pursued--and prevailed over--FlavaWorks for reimbursement of legal costs, but FlavaWorks did not respond. Last summer a Florida court ordered the seizure and sale of much of FlavaWorks intellectual property (i.e., their porn catalog) in order to pay A4A's legal costs. There's a popularized story about this at https://bananaguide.com/article/112977/flava-works-takes-hit-in-lawsuit-against-adam4adam. Philip Bleicher, principal of FlavaWorks, had the following amusing comment regarding this:
"We unfortunately hired some attorneys who turned out to be of the same caliber as Rudy Giuliani — and two of them are currently under investigation by the bar disciplinary commission and one was recently disbarred...We are cleaning up this mess, not going out of business and have filed Chapter 11 to reorganize these debits [sic]"
The Giuliani reference seems to fit, because Bleicher apparently doesn't like to pay his counsel. There's a carefully thought-through rant by an attorney retained (but not paid) by FlavaWorks at https://gulisanolaw.com/phillip-bleicher-criminial-conman-liar/. I especially enjoyed the following line from the attorney who was stiffed,
I made the following counter-offer to Mr. Bleicher: “go fuck yourself and pay me for the work I did.”
I think the bottom line is that FlavaWorks is in its death throes and cannot be taken seriously at this point. I'm not going to offer legal advice in a forum like this, but I will say that if I received a letter from FlavaWorks, I would ignore it.