Recaptcha at admin login problem

WordPress version 4.9.5, theme Doo. Everything is up to date.

My admin login has had a Recaptcha prompt for some years ago. I don’t know what I did to put it there, but it hasn’t been giving me any problems until this month. Now the captcha form says “Recaptcha V1 is shutdown”, so I can’t login again if I’m logged out.

I searched through all of my WordPress files and could only find Recaptcha mentioned in the wp-spamshield, BWS contact form, and Sucuri plugins. I disabled those plugins but I still get the Recaptcha prompt.

I tried installing a Recaptcha v2 plugin but it has no effect. I then uninstalled it.

I looked at the wp-login.php file, trying to determine where the Recaptcha is being called. I even tried adding some temporary wp_safe_redirects to a different URL at various places in the file to troubleshoot, but it still displays the Recaptcha, even if I do the temporary redirect before any other statements.

Is anyone else having this problem? How do I disable Recaptcha or upgrade it wherever it is at?