Typically that challenge occurs when the browser has no cookie saved from a previous eBay session, or when using a different IP-address.
Have you changed anything about your setup lately? New browser, or new privacy settings or software? Using a VPN or hotspot?
If you have set your browser to delete cookies when you close it, or if you use a cleaner program that periodically erases cookies, you will likely have to go through a challenge after your cookies are erased.
If you are not erasing your browser cookies, and there is nothing different about your network connection, then perhaps you have a corrupt or blocked eBay cookie. In that case, try manually erasing just your eBay cookies once. Clearing all cookies may not work in the case of a corrupt cookie -- manual deletion may be necessary.
If that does not help, try another browser altogether or a private or incognito browser window.
Preferably the latest version of a browser you have not used before, with default settings and no add-ons installed.
I generally stay signed in and do not delete browser cookies, so the only time I encounter those Captcha tests is when I try a new browser, sign in to another country's eBay site that I have not signed into before, or restart my cable modem (which causes my provider to assign a new IP-address).
