I don’t know much about generation, but this seed seems absurd. Infinite mansions, 7-city clusters, and two Pale Mansion stacks (Stronghold and Ancient City).

I truly am not an expert on seed generation in Minecraft but I thought this seemed absolutely broken and wanted to share.

Seed: 430775694505639235
Version: 1.21.11 (Java)

What I found:

Slide 1: Broken mansion spacing at -300k blocks. They are constanly spawning in triplets and ignoring the 32-chunk separation rule."

Slide 2: A 7-Ancient City cluster with a mansion inside it at around X: 9k, Z: -14k.

Slide 3: A Pale Garden 400-500 blocks wide.

Slide 4: A Woodland Mansion and Stronghold stacked inside a Pale Garden 400-500 blocks wide (at around X: 5.6k, Z: 9.2k).

Slide 5: A Mansion and Ancient City stacked inside a 400-500 block wide Pale Garden (at around X: -474k, Z: 182k).