@vanis You can fix the z-values range to be colormapped, by setting zmin, zmax in go.Heatmap`. In the example I posted answering your question https://community.plotly.com/t/colorscale-text-size/30615/2,
after plotting the initial Figure, perform the following updates to compare the corresponding colorbars:
fig.data[0].update(zmin=0.2, zmax=0.8)