There are 2 objects in the scene each with it's own material and shader, both being drawn in the opaque pass.
The "mask" draws to the stencil buffer and to the depth buffer while the "space" object checks the stencil and always writes to the depth buffer without checking it (ztest always).
Due to the nature of the depth buffer settings, there is no preferred order drawing since front to back is not going to be valid. Given there's no preferred order of drawing, the SRP batcher optimizes this for the least amount of state changes which orders by material id and shader id. Since these ids are not guaranteed to be the same between editor and player the order cannot and should not be guaranteed to stay the same. The same issue can be reproduced in the editor by duplicating the shaders and materials and finding a combination in which the order of drawing is reversed, regardless of the objects being in a subcene or not.

One easy way to fix this is to make use of the queue order in the material. By default it is set to 2000 but can be edited to force a specific ordering.

Another thing that is worth mentioning is that having the "space" shader use ztest always and zwrite yes is peculiar and depending on the exact use case could also be a mistake