ALWAYS a bad sign!
The original AGM-type batteries were nearly all sold with acid in separate packaging, which meant that they could be shipped, but also that they had to be commissioned and charged (properly) before use.
The only "development" in powersports batteries that I am aware of (apart from the LiPo/Shorai/etc.) over the past 20 years has been the widespread used of "factory activated" AGM batteries, such as the YTZ series of Yuasa batteries that were supplied as OEM on the ST1300, for example. (The heralded Odyssey AGM batteries are, AFAICT, stronger simply because they are bigger, and thus weigh more than other AGM batteries.) The battery technology used by both of these types of batteries is almost exactly the same. That said, it is possible to assemble any battery with better quality components than other brands, and certainly, some of the cheaper brands do not seem to last as long as some of the more expensive ones. But even the relatively expensive Yuasas have been known to fail internally. Consequently, you cannot guarantee a long service life by simply fitting an OEM replacement battery--it could last a long time, but it might not actually have any advantage over a cheaper battery.
Recently, I have only purchased Yuasa YTZs for my bikes, but the yellow ones (Motobatt?) seem to have earned a good rep from what I've heard. But given that a brand new, never installed, on an Optimate from day 1 Yuasa YTZ10S I have in the garage is now showing "weak" after six months I'm probably not going to be maintaining my impressive Yuasa purchase record for much longer!
Ciao,