Actually, Apple first denied to renew the signing certificate I needed to update the .kext kernel extension that is necessary to make the Hajo Headphone Enhancer work. That's why updates got delayed while I was still hoping to resolve that.

Then, like a year later, it became clear that I would need a full rewrite to make things work again because there was no way Apple would allow me to keep using the old APIs. I took a critical look at the sales numbers (like $6k over 3 years for the Hajo's Headphone Enhancer product) and decided that writing an Apple-only kernel driver from scratch would not be financially viable.

Since I was also the person that built the original Windows-only Spatial Sound Card app, I offered the burning Mac app ruins to them ;) But actually merging both products was done by my successors.