I do some similar stuff, multiple redeems when I remember that Amazon gaming is a thing, but whilst I do get captcha challenges, they are some of the easiest I’ve seen lately. So it is possibly something to do with your specific setup to access their site. No VPN here, and Firefox with Noscript and ublock does not pose any issue, though I obviously have to temp whitelist gog and gog static or whatever are their two domains for the site to even work. I think I have whatever captcha service domain they use permanently whitelisted because some important thing I need to access, related to payments, uses it.
The wire/metal holding it needs to be springy and bobbing back and forth to generate the momentum, duh… Half-assed implementation I say.