Yes, when I get the error on my laptop, the URL starts with https://www.ancestry.com/mrd?key=U
I also get the error on my phone (where I don't think I have the same cookies set that I have set on my computer). When I get the error on my phone I can't see the URL past the "key" item, but it is probably the same.
I am not getting this error when I am logged in as a project account, from a different browser, on my laptop.
When I saw it, I assumed it was a problem traceable to the WikiTree affiliate tag, and that is still my hunch. If so, it's something for the Team to discuss with Ancestry.
As has been noted, it's relatively easy to work around this particular issue (it was far, far, more difficult to work around the blockages that Ancestry used to impose me when I tried to access Ancestry any time after having once clicked on an Ancestry URL in ancestry.ca or any other Ancestry domain that was not ancestry.com), but the vast majority of WikiTree visitors who encounter this error will simply blame us for posting bad URLs.