Selenium .close() triggers WebDriverException: chrome not reachable

Question

This is my env:

• Ubuntu 20 LTS
• selenium 3.141.0
• google-chrome-stable 101.0.4951.64-1
• ChromeDriver 101.0.4951.41

I run this simple code in headless mode (I do not need the GUI):

chrome_options = Options()  
chrome_options.add_argument("--headless")
chrome_options.add_argument('--no-sandbox')
chrome_options.add_argument('--ignore-certificate-errors')
browser = webdriver.Chrome(options=chrome_options)

# get a web page
browser.get("myUrl")


# signing in...
username = browser.find_element_by_name("user")
password = browser.find_element_by_name("pass")
submit_button = browser.find_element_by_xpath("...")
username.send_keys("user")
password.send_keys("pass")
submit_button.click()
print('User logged in...')


# Click on the update button in the next page
update_button = browser.find_element_by_id('barbaz')
update_button.click()
browser.close()

This code worked fine with older versions of google-chrome-stable and ChromeDriver. Strangely enough, now browser.close() triggers this error:

WebDriverException: Message: chrome not reachable (Session info: headless chrome=101.0.4951.64)

What is happening?

Edit:

browser.quit() instead of browser.close() seems fixing. I leave this question open, in the case anyone would like to explain the reason behind that.