I've seen this issue when i have used range brass, did a search and found it mostly comes from the glock unsupported chamber. my lee carbide usually takes care of it but i still watch for it while reloading.
Redding and a few others make a push through sizing dies. Here is what happens in my experience... With some of the higher pressure loads like 40 or 10mm the brass swells and a typical sizing die cannot size the area near the base. I see this a lot with my brass that run I through an unsupported chamber like my Glock. Using a push through sizing die and a max cartige case gage after reloading assures no of these reach the chamber. I'd ask if they use a full length sizing die (which cannot re size the base). Or if they use a push through die. And I'd ask why they don't use a max case gage...
Bad case prep job. Since ammo is hard to get there seems to be a more little reloading "businesses". It seems that I am picking up a lot more live ammo off the floor at the range these days that are poorly assembled and out of spec. Being in a hurry does make more errors. I hope the place sends you some free replacements.