Deprecated function error on webform submission

What version of the recaptcha module do you have installed?
It looks like you are using an outdated recaptcha package. There are those properties in the 1.3.0 version https://github.com/google/recaptcha/blob/master/src/ReCaptcha/ReCaptcha....

I was using the latest Recaptcha V3, installed with Ludwig.

I had also uninstalled Recaptcha module which I was using till now.

However, the 1.2 library for Recaptcha was still there in Ludwig packages. It did not get removed on uninstallation, and instead there were two libraries and 1.3 was getting overridden by 1.2

Solution:
(i) Uninstalled Recaptcha V3
(ii) Uninstalled Ludwig
(iii) Cleared cache
(iv) Deleted Recaptcha from /modules
(v) Cleared cache
(vi) Installed Ludwig and Recaptcha V3

All good now.