I've noticed a similar thing with Trader Joes in PNW vs California. The produce selection was different, the pre-made foods (like the salads, wraps..etc) were somewhat different, meat selection and quality was also different.
Part of it is that TJ's used to be much more about the 'one-off buy of a weird but tasty product'. They would find a product they could sell, buy as much of it as was possible, and sell through it, never to order and sell it again. Over time though, it grew to be the store where people went for basic staples, and so the way they sourced products probably changed to a more traditional model that grocery stores use, where many of the more perishable products are regionally sourced.
So what you experienced with the Sonoma Chicken Salad (which, I commend your appreciation, that used to be a favourite of mine to get for lunch) is likely a result of them just being completely different products made in different places by different companies.
Trader Joes in the 90's and early 2000's was a cool quirky grocery store to pick up some fun stuff and good wine to round out the weekly grocery shopping. TJ's in 2024 feels like Kroger standing on Whole Foods shoulders wearing a trench coat.
