The current value for GT: Package-Level RAPL/PBM PL2, PL3, under Performance Limit Reasons is always flagged with "Yes." Does anyone know what this meansurement is associated with and what are some of the causes of it throwing an exception?
This is not an exception - it's just an information flag determining the reason why the CPU/iGPU performance level is clipped.
If it says "Yes", the particular reason has been triggered.
"GT" stands for the integrated GPU part of the CPU (iGPU), RAPL = Running Average Power Limit
So this particular reason seems to indicate a violation of package power limit (short: PL2 or system: PL3).
More information can be found in the "Intel® 64 and IA-32 Architectures Software Developer’s Manual", which is publicly available on the Intel web. This is for advanced users.
Also note, that some CPUs might contain bugs which cause that some Power Limit Reasons might not be reported properly.