Basically, what you're seeing isn’t a glitch—it's just a change in how things are done. The old version of Rbf used epsilon to directly scale the distance, so even small tweaks could really shake things up. But the new RBFInterpolator has been reworked with extra stabilization and scaling tricks that essentially "normalize" epsilon’s role. This means that even if you change epsilon a lot, its impact is much more subtle, especially if your data is already nicely scaled.