Ding has nothing to be ashamed of. He fought like a true warrior. He was a great champion, with class and brilliance. I just don't think he was physically as strong as he could be, and that affects one's ability to think as they must at that level.
All said, tho, it was definitely Gukesh's time, and being 18 has some serious benefits in terms of recovery and stamina.
I don't think 26. a4 was fighting like a true warrior, it was more giving up half your kingdom in the hope that your opponent will then accept a peace treaty.
I can't speak to the subtleties of chess, but I did watch Hikaru's recap and he was of a similar opinion.
I still think Ding was physically and/or emotionally compromised to some extent. That's why I still consider his effort lionine, because his game 12 game was masterful and he was in it until the end. I hope he holds his head high.
All said, tho, it was definitely Gukesh's time, and being 18 has some serious benefits in terms of recovery and stamina.