While the stats look good, the shape looks a bit strange.
I would assume that the number of samples would be stored in dim0 followed by the height and width.
However, somehow the shape is permuted.
Could you get a single sample from both datasets and visualize it to check, if the pixels might be interleaved?
Something like this should work:
import matplotlib.pyplot as plt

data, _ = dataset[0]
print(data.shape) # should be [28, 28]
plt.imshow(data.numpy())