That's not how exponential growth works. A ×10 increase in 1.2 years implies a ×1010 increase in 12 years. According to these numbers it should be ×10 in 6 years which roughly aligns with the end of the decade.
It doesn't matter if your password contains an illegal move, it just has to include a valid best move, then it will just ignore all illegal moves. Also captcha can be rerolled as many times as you want.
https://github.com/archlinux/archinstall/issues/3936
P.S.: This issue was not submitted by me, it just happened to be the latest submitted issue at the time of this post.