The reason that occurs is that Google is objecting to Safari's intelligent tracking prevention, which (among other privacy aspects) limits its ability to identify you, harvest your personal information, monitor your browsing activity, and retain it for their purposes — which is to sell you, as a product. It is concluding (wrongly) that your computer is a "bot" and you are not "you" for reasons I'll explain later.
Safari is specifically designed to protect your privacy whereas Google is specifically designed to exploit it.
Provided you accede to Google's privacy intrusions, your options are to use a different, non-Webkit browser. In addition to Firefox consider Brave:
https://brave.com/
Brave is Chrome without the Google. It may lack Safari's superior privacy features, but no one needs Chrome.
For reference: https://webkit.org/tracking-prevention-policy/
Excerpts:
These practices are harmful to users because they infringe on a user’s privacy without giving users the ability to identify, understand, consent to, or control them.
...
Unintended Impact
There are practices on the web that we do not intend to disrupt, but which may be inadvertently affected because they rely on techniques that can also be used for tracking. We consider this to be unintended impact. These practices include:
... and
We want to see a healthy web ecosystem, with privacy by design.
That philosophy lies at the heart of everything Apple does, and is an existential threat to Google's business model. Google is frankly desperate to infest your Mac, and is resorting to increasingly desperate measures to convince you to do that. You don't have to play that game. If Safari does not meet your requirements try Brave or Firefox.
