Lando has trouble accessing a URL from a non-Lando app on my system
From your question, it sounds like the URL you're trying to access is running on a non-Lando docker container on your machine.
This means routing from your Lando instance to the service will be a bit different that usual. You should be able to accomplish this the same way you would access localhost endpoints. As explained in this Lando issue on GitHub, you must use the $LANDO_HOST_IP environment variable to route to local services.
Since your containers are all running inside of a light hyper-v instance you'll need to know the hostname or IP of the host machine. Generally we set $LANDO_HOST_IP to your computer . . .
So try something like this (assuming you're using PHP's curl):
curl_init('http://' . $_ENV["LANDO_HOST_IP"] . ':8081/clicks-bff/api/ads/');