Why are /dev/random and /dev/urandom stopping after 32MiB?

I get this output on very single commandline listed below:

0+1 records in
0+1 records out
33554431 bytes (34 MB, 32 MiB) copied, 0.14532 s, 231 MB/s

Here are the different options I tried:

a) dd if=/dev/random of=/dev/null status=progress bs=1G count=1

b) dd if=/dev/urandom of=/dev/null status=progress bs=1G count=1

c) dd if=/dev/urandom of=/dev/null status=progress bs=100M count=1

d) dd if=/dev/urandom of=/dev/null status=progress bs=50M count=1

e) dd if=/dev/random of=/dev/null status=progress bs=50M count=1

f) dd if=/dev/random of=/dev/null status=progress bs=33M count=1

g) dd if=/dev/urandom of=/dev/null status=progress bs=33M count=1

This dd if=/dev/urandom of=/dev/null status=progress bs=10M count=1 is doing as expected and outputs:

1+0 records in
1+0 records out
10485760 bytes (10 MB, 10 MiB) copied, 0.0518184 s, 202 MB/s

I tried this with MX Linux (Kernel 5.10) and with KDE neon and with Ubuntu 20.04

Does someone have a under-the-hod answer? Or some possible ideas?