You did not pass the validation check used to prevent spam submissions

Yes, the proxy things there didnt change - but the OJS one:

;;;;;;;;;;;;;;;;;;
; Proxy Settings ;
;;;;;;;;;;;;;;;;;;

[proxy]

; The HTTP proxy configuration to use
http_proxy = "http://host:port"
https_proxy = "http://host:port"

is NEW (adapted to my needs - this is the new template: ojs/config.TEMPLATE.inc.php at 8b10104d464322e48b5dd5466a7d6f0fd3187b49 · pkp/ojs · GitHub) and:

;;;;;;;;;;;;;;;;;;
; Proxy Settings ;
;;;;;;;;;;;;;;;;;;

[proxy]

; Note that allow_url_fopen must be set to Off before these proxy settings
; will take effect.

; The HTTP proxy configuration to use
; http_host = localhost
; http_port = 80
; proxy_username = username
; proxy_password = password

was then.

Could this cause issues now? EDIT: I would say yes - because the variable name changed from http_host to http_proxy. So, for your recpatcha script, no proxy is now set.

Would be even nicer, if the recpatcha would use the generic HTTP-things (curl).