To ensure effects are rendered in a 32-bit floating-point color space, you must select "Render at Maximum Depth." This setting forces Premiere Pro to process all rendering and compositing at the highest possible precision (32-bpc). This is crucial for maintaining color fidelity, preventing banding artifacts in gradients, and preserving detail when stacking multiple color-intensive effects, which directly addresses the user's goal. The Mercury Playback Engine mode (Software or GPU) does not change the function of this export setting.

B. Choose Performance > Hardware Encoding: This setting accelerates the final compression (encoding) stage using dedicated hardware; it does not affect the bit depth of the effects rendering pipeline.

C. Use Maximum Render Quality: This option primarily improves the quality of scaling (resizing) and motion rendering by using more advanced algorithms, but it is not the specific control for 32-bit effects processing.

D. Check Render Alpha Channel Only: This exports only the transparency information of the sequence as a grayscale image, which is unrelated to rendering color effects at a specific bit depth.

1. Adobe Premiere Pro User Guide

"Export settings reference for Premiere Pro." Adobe Help Center.

Section: Render at Maximum Depth: "Renders content at 32-bpc color depth. Select this setting to maintain color fidelity and prevent color banding in videos with steep gradients. This setting is disabled if the selected codec does not support it."

Section: Use Maximum Render Quality: "This setting is most useful when you are exporting to a frame size different from your source media's frame size. Selecting this option helps maintain image quality when scaling."

This official documentation explicitly states that "Render at Maximum Depth" is the setting for 32-bpc (bits per channel) rendering

while "Use Maximum Render Quality" is for scaling.