Displacement 3D models appear pixelated in nodes mainly due to two issues: a low-resolution displacement map or insufficient sampling/preview settings in the node.
Low-res displacement maps lack enough detail to create smooth surfaces—fewer pixels mean blocky, uneven edges. Meanwhile, low sampling or preview quality in the node skips fine details, leading to pixelation.
To fix this, use a higher-resolution displacement map (2K or 4K) and adjust the node’s preview or subdivision settings to sample more detail.