I don't believe those little fins are there for structural integrity of the finished product. They are most likely just a by-product of how the mold is designed.
Not true, the "fins" are there to support/ stabilize the stem.
SA profile keycaps have much longer stems and they do not have these fins.
Your point being what? I didn't say the keycap would break without the fins, I said they're there to support the stem.
Adding the fins complicates the mold more thus making it more expensive to produce, if the fins were totally useless why would most profiles (other than stuff from SP) include them?
The addition of the fins isn't necessary but it leads to a more solid final product.
No need to get defensive, I'm just making observations based on available evidence.
I'll point to the fact that GMK representatives themselves stated that the missing fins were just a cosmetic issue.
Further, if you look under your row 3 GMK keycaps, those fins are maybe half a millimeter high. They aren't doing anything for the structural integrity of the stem.
I don't know why the fins are there, but I believe they have something to do with the manufacturing process rather than the finished product.
To answer your question, my point is that we do not need to worry about missing fins on keycaps. The deformities are strange, but regardless of why they are there, the missing fins are not detrimental to the keycaps' usability.
Of course in OP's case, where there is actually extra material protruding to where it should not be, this is certainly a problem. However, since many thousands of individuals use GMK keycaps regularly and this is seemingly the first time this issue has popped up, it is likely isolated to a small run of caps.