Why does sampling frequency affect the filter results?
Limited numerical precision. The higher the sample rate, the closer the poles move to the unit circle, the closer to the unit circle, the less stable the filter is.

There are different implementation methods that are better than others: design as poles, and zeros and not as transfer function, use cascaded second order sections, use correct section ordering, higher precision data types, etc.

In most cases very high order filters with poles close to the unit circle are a bad idea. You get very high group delay and phase distortions and massive time domain ringing.