Looks like you’ve lost the carbide tip. Either plunging too fast or allowing some movement while in the plunge. Since you have lost two now it makes me think user error, especially since the first few plunger were okay. The carbide is probably in the bottom of a mortise or somewhere on your floor. I feel bad about pointing the finger at you but 2 occurrences kind of rules out a bad brazing job. Like others, I have not experienced loss of size over many, many uses including in Ipe.