I’ve been reading a book and where I left off, just today, talks about how LME rapidly degrades.
“Because malt extract is a highly concentrated mix of water, sugar, and protein, it has all the elements necessary for a Maillard browning reaction, even at room temperature, which can result in beer with an unpleasant lingering flavor that my colleagues in Chicago refer to as “ball-point pen” flavor. The term “cidery” is also sometimes used in this context. This browning reaction causes malt extract to darken as it ages, and also during manufacture, so it is often nigh impossible to brew an extremely pale beer, like a German-style Pilsner, with liquid extracts. Spray-dried extracts have a bit better track record for becoming stale and darkening, but they are not immune. Freshness matters, so find out which malt extract brands sell the fastest at your supplier, and stick to those.“
-Mastering Home Brew, Randy Mosher
with that being said, I would absolutely brew that kit unless there was something obviously off.