Yes - you really pay for those flat Fen sections. I didn't even make it to the Moss, the 20%ers between Malton & Barny did for me. By the time I got to BC I'd run out of spoons. Not sure that free routing would have made much difference tbh, at least not in that bit. What looked reasonably benign (113km. 1200m) turned into a real horror....
The gpx file for Malton to Barnard Castle in gpxeditor says 1645m over 113km. Which is 14.5 m per km. That's a bit tasty. The profile doesn't look too bad (to me, viewed from my sofa)
Generally, lots of little climbs are worse than a few large climbs
Usually, crossing moors in the North of England is arduous. But the views are good. Although it was far too hot, it must have looked loverly
If I was planning to do this I'd probably estimate it would take a while. But I probably would have used the lower number from the summaries on the web page (1200m) that you mentioned!
The question that you and others are asking is: is it surprising, given the info from the event orgs that the particular route this time is difficult? And is this route more difficult than necessary?
No, it isn't surprising
Yes, the route is more difficult than it could possibly be. But events in 2022 tend to favour quiet, pretty roads. I'm sure making it difficult isn't a priority