[Bug]: Change in ListedColormap behavior in 3.10.0 #29504

import numpy as np
from matplotlib import pyplot as plt
from matplotlib.colors import ListedColormap
from matplotlib import __version__ as mpl_vers


cld_type_colors = [
    "ghostwhite",
    "slategray",
    "blue",
    "royalblue",
    "cyan",
    "limegreen",
    "green",
    "yellow",
    "gold",
    "lightsalmon",
    "coral",
    "red",
    "maroon",
    "black",
]


rainbow_colors = [
    (255, 0, 0),     # Red
    (255, 64, 0),    # Reddish-Orange
    (255, 128, 0),   # Orange
    (255, 192, 0),   # Yellowish-Orange
    (255, 255, 0),   # Yellow
    (192, 255, 0),   # Yellowish-Green
    (128, 255, 0),   # Greenish-Yellow
    (0, 255, 0),     # Green
    (0, 255, 128),   # Greenish-Cyan
    (0, 255, 192),   # Cyan
    (0, 255, 255),   # Bright Cyan
    (0, 192, 255),   # Bluish-Cyan
    (0, 128, 255),   # Blue
    (0, 64, 255),    # Blueish-Purple
    (64, 0, 255),    # Purple
    (128, 0, 255),   # Violet
]
rainbow_colors = [(r / 255, g / 255, b / 255) for r, g, b in rainbow_colors]

cld_type_cmap = ListedColormap(cld_type_colors, name="cld_type_cmap")
rainbow_cmap = ListedColormap(rainbow_colors, name="rainbow_cmap")

# Create 1600x1600 array constant values in the vertial and float values ranging from
# 0-15 in the horizontal
size = 1600
num_values = 16
h_vals = np.linspace(0, num_values - 1, size)
flt_array = np.tile(h_vals, (size, 1))

# Plot float values using the cloud type colormap
fig, ax = plt.subplots(figsize=(10, 10))
ax.set_title("Float - Cloud Type Color Map - MPL Version: " + mpl_vers)
ax.imshow(flt_array, cmap=cld_type_cmap)
fig.savefig(f"float_cloud_type_{mpl_vers.replace('.', '')}.png")

# Plot float values using the rainbow colormap
fig, ax = plt.subplots(figsize=(10, 10))
ax.set_title("float - Rainbow Color Map - MPL Version: " + mpl_vers)
ax.imshow(flt_array, cmap=rainbow_cmap)
fig.savefig(f"float_rainbow_{mpl_vers.replace('.', '')}.png")

# Create a 1600x1600 array constant values in the vertial and integer values ranging
# from 0-15 in the horizontal
h_vals = np.arange(0, 16)
h_vals = np.repeat(h_vals, size // len(h_vals))
int_array = np.tile(h_vals, (size, 1))

# Plot integer values using the cloud type colormap
fig, ax = plt.subplots(figsize=(10, 10))
ax.set_title("Integer - Cloud Type Color Map - MPL Version: " + mpl_vers)
ax.imshow(int_array, cmap=cld_type_cmap)
fig.savefig(f"int_cloud_type_{mpl_vers.replace('.', '')}.png")

# Plot integer values using the rainbow colormap
fig, ax = plt.subplots(figsize=(10, 10))
ax.set_title("Integer - Rainbow Color Map - MPL Version: " + mpl_vers)
ax.imshow(int_array, cmap=rainbow_cmap)
fig.savefig(f"int_rainbow_{mpl_vers.replace('.', '')}.png")