As from django 4.1 CheckConstraint are evaluated during the Model.full_clean process using model data.

As of now this does not work with netfields since the checker does not produce the right query (see https://github.com/sevdog/netfields-check-error for reference).
With a check constraint like the following:

CheckConstraint(check=Q(network__net_contains=F('inet')),name='inet_contained')

the ORM produces the following query:

SELECT 1 AS "_check" WHERE COALESCE(('192.168.0.0/24' >> ('192.168.0.1')), true)

which raises an error on Postgresql since

operator is not unique: unknown >> unknown [...]
HINT: Could not choose a best candidate operator. You might need to add explicit type casts

Thus if this is called inside a transaction then any following query will fail since the transaction is not on a clean state and raising

current transaction is aborted, commands ignored until end of transaction block

Looking at similar issue on django (see https://code.djangoproject.com/ticket/34059) the solution seems to be adding a new method Field.get_placeholder which is used by ORM to insert values in this process.