I've noticed every
rel="noopener noreferrer" link with
target="_blank" we add to our sites automatically also get a 'nofollow' added to the rel attribute, when I inspect them in dev tools. I'm pretty sure it has to be added by the browser, because when I check the page source in the browser, only noopener and noreferrer are there.
I mainly use Brave on MacOS, but Chrome, Firefox and Safari show the same behaviour.
What could cause this?