Nice looking trailer with all the exterior black trim and other black things.
๐Fluid Film is a great product for use on squeaky leaf springs. Don't use anything that will attract dirt and don't let the dealer do that either. I would spray something on yourself as it will get done faster and probably better than a dealer can. Not certain, but it might help to jack the frame up to relieve pressure on the springs.
Squeaky leaf springs is common on boat trailers due to frequent water immersion and then sit for a while between use. If your TT sat on a lot for about a year, it could have built up a coating of rust on the springs, esp. if it was delivered in the winter with salt on the roads.
Potentially could also be the pivot points in the suspension. I'd inspect the bushings in springs and equalizers. The standard plastic bushings they use are quite thin and can wear out quickly. On a previous TT, ours were all totally shot from when we took ownership, but that was after about a 2K mile delivery to the west coast. We have Dexter wet bolts, but Lippert's Never-fail bushings are an option too. I'd try spraying something onto the springs first.
Also maybe check anything abnormal looking in the suspension. If it's not the leaf springs, I'd be asking the dealer to look at it, but perhaps after the end of the season otherwise it can take them weeks to get around to even simple jobs.
FWIW, you might want to look at anything steel under your TT and see if much or anything is rusting. If exposed to salt, you can expect to find rust happening in various places. If so, I'd thoroughly wash it and plan on doing some painting. Maybe next season when it's warmer and dryer for a while. Our TT was delivered in the winter and has a lot of rust everywhere, including bolts that *used* to be plated.