@audio_is_subjective "...or filaments maybe getting damaged in shipping?".
Possibly so. No joke. I had a particular 6SN7 tube I was buying from a specific distributor overseas who densely cotton packed, bubble wrapped, and then double boxed quad sets I was buying. No problems for me on any of them, shipped from over seas to me direct. Many drop changes too, along the way. Others, were having issues with the exact same tubes. Nobody could figure out what was going on. They chased it down. Took a while for the manufacturer to figure it out.
Two years later they figured out they were shipping these large boxes of 100 units (or so) well packed, to a US Distributors who was taking them out of those specially packed boxes, and poorly repacking them in other cheap packaging as individual or pairs and sending them out. All the sudden this distribution channel had problems. People blamed the tubes themselves, and yet it was poor re-packing and shipping damage occurring. Recalling photos, the US distributor put NO time, care, $, or effort into the repackaging and boxing. THIS created a real problem for the reputation of the manufacturer. Was unfortunate, this created other business issues too.
ASK:
Ask your tube reseller to explain exactly how they get shipped out or send you a few photos before shipping them out. If they won’t do this, move to a different tube reseller. Best of Luck!