Bug submission form captcha doesn't work 95% of times

Tried in Firefox 83→nightly, nineteen times out of twenty it says “Invalid captcha”.
I am positive it was not invalid, something must be wrong with it.

If I pause the script that fires after I click that button for a second via browsers development tools, it works every single time.

Question: how hard could it be to not ■■■■ up captcha in 2021?