Forwarding unknown arguments and options to commands using Context.forward

Question

I try to build a command line application that has several single commands with different options, but also a general command which should execute every single command as well.

The code looks currently like this:

import click


@click.group()
def cli():
    ...


@cli.command('mod1', context_settings=dict(ignore_unknown_options=True, allow_extra_args=True))
@click.argument('arg1')
@click.argument('arg2')
@click.option('--option1')
@click.pass_context
def mod1(ctx, arg1, arg2, option1):
    print('Running mod1')
    print(ctx.params)
    print(ctx.args)


@cli.command('mod2', context_settings=dict(ignore_unknown_options=True, allow_extra_args=True))
@click.argument('arg1')
@click.argument('arg2')
@click.option('--option1')
@click.option('--option2')
@click.pass_context
def mod2(ctx, arg1, arg2, option1, option2):
    print('Running mod2')
    print(ctx.params)


@cli.command('mod3', context_settings=dict(ignore_unknown_options=True, allow_extra_args=True))
@click.argument('arg1')
@click.pass_context
def mod3(ctx, arg1):
    print('Running mod3')
    print(ctx.params)


function_mapping = {
    'mod1': mod1,
    'mod2': mod2,
    'mod3': mod3,
}


@cli.command('all', context_settings=dict(ignore_unknown_options=True, allow_extra_args=True))
@click.argument('arg1')
@click.argument('arg2')
@click.option('--option1')
@click.option('--option2')
@click.pass_context
def main(ctx, arg1, arg2, option1, option2):
    print('Running all commands')
    print(ctx.params)
    print(ctx.args)
    for mod in function_mapping:
        ctx.forward(function_mapping[mod])

if __name__ == '__main__':
    cli()

The problem is, that whenever mod1 is executed, the script fails with the error message TypeError: mod1() got an unexpected keyword argument 'option2'. According to this link, paragraph 1, this should work and extra arguments are captured to ctx.args.

Click version used here is 8.0.4, Python 3.8.10.

Any ideas or hints on this? Many thinks in advance.

EDIT Is has something to do with ctx.forward. If I specify mod1 as command and add any other option, it works and those unknown options are seen in ctx.args.