The discrepancy in reported image memory may be due to compression, mipmapping, or engine-specific optimizations. Modern GPUs handle non-power-of-two textures well, and memory is often influenced by viewport size and scaling. To reduce image memory, consider using compressed formats and optimizing resolutions.
This is, I'm afraid, in the context of Construct and this discussion, largely nonsense.
If you are using AI to generate replies, don't do that. It will generate things that sound plausible but are in fact completely irrelevant and misleading.