Differences in "procedure locking" based on the way the client is connecting to the database

I have created a test procedure like that:

CREATE OR ALTER PROCEDURE tmp_fab
RETURNS (dummy INTEGER) AS
BEGIN
    dummy = 1;
    suspend;
END

Then a first client ("client A") uses the procedure by executing the following SQL:

SELECT *
FROM tmp_fab

If another client ("client B") tries to alter the procedure (while the "client A" transaction is still active and not committed/rolledback), I see a different behaviour based on the way the "client B" is connecting to the database.

For example:

Trying to alter the procedure as follows:

CREATE OR ALTER PROCEDURE tmp_fab
RETURNS (dummy INTEGER) AS
BEGIN
    dummy = 2;
    suspend;
END

While committing the "client B" transaction...

It fails, with the following error:

Unsuccessful execution caused by system error that does not preclude successful execution of subsequent statements.
Lock conflict on no wait transaction.
Unsuccessful metadata update.
Object PROCEDURE "TMP_FAB" is in use.

• Using FireDAC Delphi components (DriverName = FB)
• Using FIBPlus Delphi components
• Using IBExpert (It uses it's own firebird's dll)

It succeeds, correctly altering the procedure...

• Using isql
• Using DBeaver (It uses JDBC)
• Using FireDAC Delphi components (DriverName = ODBC)

Which is the cause of these two different behaviors? (Maybe some transaction settings?)