import matplotlib.pyplot as plt
x = range(10)
lab = "foo bar baz"

# with extra space it works, but the second plot with two lines gets
# clipped.
fig0, axes0 = plt.subplots(1, 2, constrained_layout=True)
[ax.plot(x, x) for ax in axes0]
[ax.set_ylabel("\n".join([lab]*(i+1)),
               y=1.0,
               rotation="horizontal",
               horizontalalignment="left",
               multialignment="left",)
 for i, ax in enumerate(axes0)]

# single plot with one line also gets clipped
fig1, ax1 = plt.subplots(constrained_layout=True)
ax1.plot(x, x)
ax1.set_ylabel(lab,
               y=1.0,
               rotation="horizontal",
               horizontalalignment="left",
               multialignment="left",)

# For reference it works fine when placing the ylab on the 'side'
# as a conventional matplotlib plot
fig2, ax2 = plt.subplots(constrained_layout=True)
ax2.plot(x, x)
ax2.set_ylabel(f"{lab}\n{lab}",
               rotation="horizontal",
               horizontalalignment="right",
               multialignment="right",)

for i, fig in enumerate((fig0, fig1, fig2)):
    fig.savefig(f"fig{i}.png")