ChromeDriver ERR_SSL_PROTOCOL_ERROR despite --ignore-certificate-errors

I'm trying to run integration tests on a local host (with no HTTPS) using selenium with ChromeDriver.

Chrome requires an https certificate, but from this question i understand that i can circumvent this using the arg --ignore-certificate-errors

I have also added to my capabilities acceptInsecureCerts, as this seems like the appropriate course of action (docs)

The response from the chromedriver is still not what I was expecting:

This site can’t provide a secure connection app sent an invalid response. ERR_SSL_PROTOCOL_ERROR

My code is below:

from selenium import webdriver
from selenium.webdriver.chrome.options import Options

# make options (principally to ignore certificate)
options = webdriver.ChromeOptions()
options.add_argument('--ignore-certificate-errors')

# add acceptInsecureCerts
capabilities = options.to_capabilities()
capabilities['acceptInsecureCerts'] = True

print(capabilities) # see below

driver = webdriver.Remote(
    command_executor=SELENIUM_HUB,
    desired_capabilities=capabilities
)
print(driver.__dict__) # see further below

app_login_url = 'http://app:8000/accounts/login/'

driver.get(app_login_url)

My capabilities:

{'acceptInsecureCerts': True,
'browserName': 'chrome',
'goog:chromeOptions': {'args': ['--ignore-certificate-errors'],
                        'extensions': []},
'platform': 'ANY',
'version': ''}

Here is my driver info, it looks like only the acceptInsecureCerts arg has been taken into account:

{'_file_detector': <selenium.webdriver.remote.file_detector.LocalFileDetector object at 0x7fb42bde10f0>,
'_is_remote': True,
'_mobile': <selenium.webdriver.remote.mobile.Mobile object at 0x7fb42bb5e400>,
'_switch_to': <selenium.webdriver.remote.switch_to.SwitchTo object at 0x7fb42bdd4898>,
'capabilities': {'acceptInsecureCerts': True,
                'acceptSslCerts': True,
                'applicationCacheEnabled': False,
                'browserConnectionEnabled': False,
                'browserName': 'chrome',
                'chrome': {'chromedriverVersion': '74.0.3729.6 '
                                                    '(255758eccf3d244491b8a1317aa76e1ce10d57e9-refs/branch-heads/3729@{#29})',
                            'userDataDir': '/tmp/.com.google.Chrome.vc1ZvB'},
                'cssSelectorsEnabled': True,
                'databaseEnabled': False,
                'goog:chromeOptions': {'debuggerAddress': 'localhost:40815'},
                'handlesAlerts': True,
                'hasTouchScreen': False,
                'javascriptEnabled': True,
                'locationContextEnabled': True,
                'mobileEmulationEnabled': False,
                'nativeEvents': True,
                'networkConnectionEnabled': False,
                'pageLoadStrategy': 'normal',
                'platform': 'Linux',
                'proxy': {},
                'rotatable': False,
                'setWindowRect': True,
                'strictFileInteractability': False,
                'takesHeapSnapshot': True,
                'takesScreenshot': True,
                'timeouts': {'implicit': 0,
                            'pageLoad': 300000,
                            'script': 30000},
                'unexpectedAlertBehaviour': 'ignore',
                'version': '74.0.3729.169',
                'webStorageEnabled': True,
                'webdriver.remote.sessionid': '1cf77f237e966bac6ca15d4d9c107423'},
'command_executor': <selenium.webdriver.remote.remote_connection.RemoteConnection object at 0x7fb42be0cf98>,
'error_handler': <selenium.webdriver.remote.errorhandler.ErrorHandler object at 0x7fb427d08a20>,
'session_id': '1cf77f237e966bac6ca15d4d9c107423',
'w3c': False}

Why am i still seeing the ERR_SSL_PROTOCOL_ERROR ?

from ChromeDriver ERR_SSL_PROTOCOL_ERROR despite --ignore-certificate-errors