OP said it was a disgusting, horrible old wet sock, man that just doesnt sound like a juicy peach. Its not a bad flavor at all really, but Ive only had it in glass.
ETA: Horrible wet sock could be a VG problem. ... I have heard that a certain vendor sells nicotine with a very distinctive odor as well.
It's not common for a well-known flavor from a well-known vendor to change. It is common for us to change brands/batches of VG, PG, & nic...and any one of those three things could definitely be the cause.
"Stale" is commonly used to describe the flavor of PG. Hubby n' me have been "100 VG" for quite some time, and just went back and tasted some HS tobaccos we'd made with some PG a few months back (30% PG/70% VG). They were disgusting...and had a distinct 'stale locker room thing' happening. But we didn't 'taste that' when we vaping PG/VG mixes.
Of course, you may not have changed anything - and if you haven't, then 'everything above' is suspect.
A month or so ago we switched brands of VG, and idiotically mixed up a few thousand mls without first testing it. It ruined the juices (making them "dead" and desperately flat/flavorless and kinda stale).
We've had 3 different brands of VG nic (ECX, Nude Nic and WZL). The WZL (two different batches) is strongly-enough flavored that we'll only use it in tobacco juices. Other brands/vendors are allegedly even more strongly flavored. (Nude Nic is far & away the most flavorless!)