As covered in the existing questions here and here, you may only customize or remove the Unity splash screen if you have a Unity Plus, Pro, or Enterprise licence. If you're using the free version of Unity, then legally you must leave the splash screen as-is. (Even if you have a clever workaround that lets you change the data without the Unity editor offering you that option, it's still a violation of the EULA)
Assuming you have a licence from Unity allowing you to modify this splash screen, your treatment of Unity's trademarks is still governed by the published Guidelines for Using Unity Trademarks and Style Guide for Permitted Uses.
Since Unity may choose to update these documents at any time, I won't try to reproduce the full rules here in this answer. Just be aware that this type of brand guideline tends to include...
Minimum spacing between the mark and other content.
Not presenting the mark in a way that implies authorship, ownership, endorsement, or sponsorship of your product by Unity.
Not filling the mark with gradients, images or textures, or changing it from filled to stroked.
Not putting the mark over a noisy background image.
Not distorting the mark.
Not re-arranging the mark and logotype outside the provided options.
Currently the published guidelines state:
Use official, unmodified Unity Logos. Each Unity Logo is an artistic asset. As such, you may only use those Unity Logos from the download source indicated to you by Unity or reproductions of master artwork provided by Unity, and you must follow any Unity Logo style guide made available by Unity. The Unity Logos may not be altered or modified in any way, including by changing the colors, changing the font, applying strokes, rearranging elements of the design, or stretching/distorting. Nor may Unity Logos be animated. Clear and consistent use is required.
I'd argue that pixelating the mark constitutes "modifying it in any way" and so would be forbidden. Unity would be within their rights to ask you not to use their mark in a way that breaks the above rules (though you could choose to simply omit the logo / splash screen entirely).
You can try negotiating alternative terms with Unity if you want to do something outside the ground rules they have set. It's always possible for them to issue you a customized licence if they're happy with the presentation you propose.