Is there an issue using a vector 3 in place of blank normal map

I’m trying to reduce the number of texture samplers in an asset of mine, and I’m wondering if setting up a vector3 in place of a blank normal as shown in the picture below is troublesome for any reason. It looks no different to me.

I would imagine that it’s the same thing mathematically. I wonder though if it’s more or less intensive though. For example, you could use a blank normal texture at 8x8 resolution. If a texture sampler is just more expensive by default then a vector 3 would definitely work. If there’s any issues you’ll get an error when you save.

Texture samples are much more expensive than a simple vector 3.
And yes, you can use a vec3 as a replacement.