The pixel area used for RSLC normalization is computed using an approximate estimation of ground velocity

[gshiroma]

The pixel area used for RSLC normalization is computed using an approximate estimate of ground velocity. The variation in ground velocity across the radar grid is not negligible. Ground velocity depends not only on the topography but also on the off-nadir angle, which can vary significantly over a wide swath.

This issue is mentioned in this comment.

[hfattahi]

Let's quantify the impact before any modification in future.