Steps to reproduce:

Create a new project with the Universal 2D template
Create a sprite (Assets > Create > 2D > Sprites > Square) and a Rule Tile (Assets > Create > 2D > Tiles > Rule Tile), and set the Rule Tile's Default Sprite to the Square sprite
Create a Tilemap (GameObject > 2D Object > Tilemap > Rectangular), open Window > 2D > Tile Palette, create a palette, drag the Rule Tile into it and paint 10 cells
Save the Scene and make a copy of its .unity file (or commit it to version control)
Reopen the Scene (File > Open Scene), move the Grid GameObject slightly and save the Scene
Compare the .unity file with the copy, then repeat step 5 and compare again

Actual results: Each save changes the Tilemap's m_TileColorArray: m_RefCount goes from 10 to 20, then back to 10 on the next reopen and save, and keeps alternating

  m_TileColorArray:
  - serializedVersion: 2
    m_RefCount: 20
    m_Data: {r: 1, g: 1, b: 1, a: 1}

Expected results: The Tilemap data in the Scene file does not change, and m_RefCount stays at 10

Reproducible with versions: 6000.7.0a6, 6000.7.0b6, 7000.0.0a12

Not reproducible with versions: 6000.0.85f1, 6000.3.27f1, 6000.6.7f1, 6000.7.0a5

Tested on (OS): Windows 11 Pro