Dash App fails to boot when using latest dash-bootstrap-templates update (1.2.0)

Hello,
I have multiple dashboards running in docker containers that restart every morning. Today, when building the containers, they failed to boot with the following error message:

[...]
 File "/usr/local/lib/python3.8/dist-packages/aio/aio_theme_switch.py", line 35, in ThemeSwitchAIO
    themes: tuple[str, str] | list[str] = (dbc.themes.CYBORG, dbc.themes.BOOTSTRAP),
TypeError: 'type' object is not subscriptable
[2024-06-20 08:26:17 +0000] [9] [INFO] Worker exiting (pid: 9)
[2024-06-20 08:26:17 +0000] [7] [ERROR] Worker (pid:9) exited with code 3
[2024-06-20 08:26:17 +0000] [7] [ERROR] Shutting down: Master
[2024-06-20 08:26:17 +0000] [7] [ERROR] Reason: Worker failed to boot.

I figured out that this is related to updates to the dash bootstrap templates. After specifying the previous version for dash-bootstrap-templates in the requirements.txt, everything worked again.

#excerpt from the requirements.txt:
dash-bootstrap-components>= 1.5.0
dash-bootstrap-templates==1.1.2 # worker fails to boot when using the newest version

Usage of dbc/figure templates:

server = flask.Flask(__name__)
app = dash.Dash(__name__,  external_stylesheets=[dbc.themes.DARKLY], server = server) 
#setting the default plotly theme
load_figure_template(themes = 'darkly')

What’s wrong, here?