Zooming in is easily defined: when you zoom into an on-state OTCA metapixel, you can check which pixels that make up the metapixel are on and which are off [1]. Same deal for zooming into an off-state OTCA metapixel. The reason you are seeing mostly dead pixels is that most pixels inside an OTCA metapixel are off, so the chance of hitting a pixel that is on is slim.
Zooming out is more tricky: when zooming out of an on-state pixel, that pixel could be at many possible positions inside an on-state or off-state OTCA metapixel. In their blog post the author says that they randomly select from the possible options in a way that adds "diversity" [2]. I think this could be improved to align with the statistics of zooming in.
[1]: https://conwaylife.com/wiki/OTCA_metapixel [2]: https://blog.oimo.io/2023/04/10/life-universe-en/#fnref5