I found a bug (at least in my case, using Firefox method for resolve Recaptcha V2 using API):
Capmonster adds a slashbar in the end of "pageurl" parameter. I'm not sure if this is happening only on the last version, but now seems relevant at least.
As my site has a query string, this affects the content of page loaded in embedded browser (I saw this info after enabling the option "Show browser" and looking at the sourcecode from loaded page).
Besides that, I made an Url Encode, just for this query string part.
So, the original URL was:
https://mysite.com/site.php?param1=aaaaa¶m2=bbbb
After the changes the new parameter is:
https://mysite.com/site.php&3Fparam1=aaaaa¶m2=bbbb&
Notice the last %26 ('&' symbol), I added this to make that wrong slashbar added by Capmonster API useless.
Making these changes, the "fake tokens" disappear. Maybe this change will keep the proxies alive for more time?
One more thing:
After the last update, if the user has IPV6 proxies and the final website doesn't support IPV6, most tries (maybe all?) will fail, because the embedded browser cannot load the informed pageUrl properly.