On average, new cars depreciate 15-20% after 1 year and 25-30% after 2 years. You have a 2024 which in 1 month, will be 2 model years old, regardless of when you purchased. In 2024 a Fieldmaster MSRP was $79,000 and change, call it $80,000 for simplicity. 30% of $80,000 is $24,000 bringing expected depreciation to $56,000. Add to that the fact that you are talking about a trade in instead of a private sale, you should always assume a lower trade in value. Then consider the relatively lethargic economy, the Inventory of new Grenadiers on the lots and the incentives for them, and the overall lack of brand awareness and lack of a brand reputation (like say Toyota).
I'd say the trade in offer makes sense and that your Grenadier is on par with typical depreciation. Yes, I fully understand that you probably got some additional options, but most of the Ineos options fall under what is traditionally viewed as an aftermarket modification (winch, rock sliders, etc), despite coming from the factory / dealer. Rarely do people realize any added value on aftermarket modifications, especially true of trade in scenarios.
Near me, on Kelly Blue Book I'm seeing about a half dozen used 2024 Fieldmasters for sale (not trade in) between $65,000-$70,000 with 2,000-11,000 miles. A private sale might be a better option.
I'm sorry you're not happy with the trade in value and that you're deciding to part with your Grenadier, but I wouldn't expect differently. I love my Trialmaster, and I'm sure if I needed to part with it I wouldn't be happy with the trade in offer either but it seems inline what I'd expect.