Instead of steam downloading at the set amount, it downloads at full speed for a bit then stops, then again downloads at full speed then stops in a repeating cycle. The cycles will repeat faster when setting a limit closer to the maximum bandwidth available, and slower when setting the limit lower and lower.
It used to follow the limit just fine but now it changed to this behavior, the issue is annoying because downloading at full speed affects my ping but setting a limit slightly bellow the maximum rate doesn't.