I counted more than that just on the Similar Threads suggestions at the bottom of this thread. If you including any GM vehicle using this engine not just Yukons and also include other vehicles of the same platform using other variant engines, the problem is a lot bigger than 3. Again that points to manufacturing/assembly issues not specifically L87 architecture issues.
I reviewed the 5x "similar threads" below (which came up for me, might be different for you, I don't know the forum algorithm) One was a fuel injector, one was battery, one was transmission control module, one was lifters, one the OP never came back and said what the issue was.
None were "bottom end" (crank shaft, rod bearings, etc).
I do agree that we have seen more than usual as of late reported here, but I don't recall seeing info
on this forum that indicates a
large issue w/ "bottom end" issues. That said, like Geotrash said, we don't have a way to extrapolate to everyone, not everyone reports in..and agree, bottom end issues were super rare to non-existent in the prior generations...so, seeing 3 here might be cause for concern, or it could be a bad lot of something, or a bad run, etc...which is why I suggested it might be interesting to see the manufacture date of the failed engines.
As an aside, saw that GM is shutting down Fort Wayne assembly for 2 weeks to "manage inventory." I read that as "pickups are not selling now, and they don't want to have to incentivise them." This may be good for meeting the demand of replacement engines people are waiting on?