Screenshotmachine - Invalid key

Since some time the rendering of the thumbnails is broken. I want to use screenshotmachine, which seems to work fine. Unfortunately there is no documentation.
I would be curious how a proper api key for screenshotmachine looks like?
I’ve tried several combinations like the whole string or just the key itself, but i don’t get it to work again …

Thank you

That may be a bug. I’ll investigate