If there's anything I like to see when I read about a table tennis blade's composition, it's the word spruce. On paper, it doesn't seem very impressive. It's light and not too hard, which is the opposite of what most people want today with the new 40+ ball... But it's elastic, so even if many offensive blades can seem slower than random allround blades at first, it can speed things up when necessary. But the best part, I think, is that it makes the blade feel alive and manageable.
But there's a downside to spruce blades. Sometimes the plies want to go separate ways, which results in a broken blade.
On the picture below, a Stiga Diamond VPS, claimed to be completely new (source):
A Victas Koji Matsushita, seemingly well treated without dents:
That one looked the same on both sides. I also had a Stiga Offensive Classic Carbon with the same symptom.
These blades share one thing and you already know what: Spruce. (Maybe the same problem occurs on blades without it, but I sure haven't seen it.)
Then I remembered something I read on the adhesive manufacturer Great Plane's website:
"Some surfaces, such as plywood, spruce and balsa, have a natural acidic content which may blend with the acidic stabilizers in the CAs, overstabilizing them. This could cause CA to take longer to cure or to not cure at all. It is for this reason that Pro CA is a 'surface insensitive' CA. This makes the glue adhere well to all surfaces, especially balsa wood. Sometimes activator may be required to speed the glue's curing process and increase the strenth of the bond."
CA stands for cyanoacrylate, which is the subject that many thin, fast and extremely strong hobby and industrial adhesives are based on, like the Great Planes Pro CA mentioned above, or Loctite glues such as the incredible 406 or the more environmental 416, or the universal 420 that Loctite themselves suggested to me once.
Could it be that maybe the TT manufacturers simply have used the wrong type of CA glue when they've used up all the right one?