A lot of DOIs point to Elsevier's linking hub, which uses browser based redirects, i.e.
https://linkinghub.elsevier.com/retrieve/pii/S0305049198000224
returns a 200 and the page content include the following meta tag:
<meta HTTP-EQUIV="REFRESH" content="2; url='/retrieve/articleSelectSinglePerm?Redirect=https%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0305049198000224%3Fvia%253Dihub&key=07cc720d5d7c8d9451bc53530e33b8df38f1ecce\'"/>
This is an issue for transitioning to translation-server-v2 as it will just scrape the redirect page and return those results.