I got this
"Destination not working: To help make sure that our ads are relevant, useful, and easy to interact with, we don't allow ads to link to broken pages. For example, your landing page can't be under construction or down for maintenance. To run your ad, make sure that you entered the right destination parameters and that your site works properly for all browsers, across all locations.
If you use App engagement ads, check if you have set up your deep link URL correctly and that you are not using a 3rd party redirect URL. This is not supported for app engagement ads."
and I'm not sure how this can be because I used the link that google/youtube forced me to have for my youtube channel which is incredibly long and unfortunately you need 100 subscribers before you can change your url to something more manageable.
which seems to work fine but supposedly it goes over their limit by like 13 characters. THey dont even let me have a tiny url. If I could get 100 subscribers I wouldn't need to use the ad service.