Maximum Render Quality helps preserve details and avoid aliasing when scaling to a frame size different from your source media. For example, exporting from a high-resolution 4K sequence to a lower resolution HD or SD format. Enabling this option can improve quality but keep the following in mind:
Export times can increase significantly, especially on systems without a supported GPU.
Systems with supported GPU hardware automatically use maximum render quality if Renderer is set to Metal, CUDA, or OpenCL. Leave this setting deselected in those scenarios.
This option is only useful when exporting to a different frame size. If you’re exporting at the same frame size as your source media (like rendering/transcoding a UHD sequence in UHD resolution), leave this setting deselected.