OverflowError fig.savefig() triggered by dpi

I have ran into OverflowErrors from Matplotlib a few times. As an easy solution, I found to increase the chuncksize:

matplotlib.use('Agg')
matplotlib.rcParam['agg.path.chuncksize'] = 20000000 # 20M

For a timeseries plot with datetime index of 64k samples, I can save a figure without specifying the dpi. After a certain threshold (somewhere around dpi=260), I trigger the OverflowError.

I thought this was quite interesting cause I thought this error was only caused by too many samples in timeseries. Can anyone explain me why this is and whether this is an issue or whether I just use a too high dpi?

Python 3.9.1, Matplotlib 3.3.3, Windows 10

Edit: Code to reproduce

import numpy as np
import matplotlib
import matplotlib.pyplot as plt

matplotlib.use('Agg')
matplotlib.rcParams['agg.path.chunksize'] = 20000000

x = np.linspace(0, 100, 100000)
y = np.random.randint(1, 100, 100000)

fig = plt.figure()
plt.plot(x, y)

try:
    fig.savefig('Figure.png', format='png')
    print('Successfully plotted without dpi')
except Exception as e:
    print(e)
try:
    fig.savefig('Figure.png', format='png', dpi=500)
    print('Successfully plotted with high dpi')
except Exception as e:
    print(e)

Results for me in:

Successfully plotted without dpi
Exceeded cell block limit (set 'agg.path.chunksize' rcparam)

Process finished with exit code 0