Problem with accessing Shadow DOM Tree with Python Selenium

I am trying to access a deeply nested Shadow DOM on the page: https://express.adobe.com/tools/remove-background

Within one of the shadow DOMs is the element I need to access (the file input element).

I am currently trying this:

sptheme = driver.find_element(By.TAG_NAME, "sp-theme")
container = sptheme.find_element(By.ID, "quick-task-container")
shadow_root = container.find_element(By.TAG_NAME, "cclqt-remove-background").shadow_root
sptheme2 = shadow_root.find_element(By.TAG_NAME, "sp-theme")

I get this error due to the 4th line above:

selenium.common.exceptions.InvalidArgumentException: Message: invalid argument: invalid locator

Element Hierarchy (I believe) to the element I wish to access:

  -tag sp-theme
    -id quick-task-container
      -tag cclqt-remove-background
         -SHADOW DOM
           -tag sp-theme
             -tag cclqt-workspace
               -tag cclqt-image-upload
                 -SHADOW DOM
                   -class cclqt-file-upload__container 
                     -this should be where the element is, with the ID: 'file-input'

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