Caveat here is that I'm not British and I don't really read British media that much, so this might not apply to those who do, but do I feel that Thomas is slightly underappreciated and has not really been taken as seriously as he deserves. Maybe because every year since 2019 has brought the 'is he done now?' discussion, only for him to prove everyone wrong a few months later, after that discussion has already been concluded in his disfavour.
His standing as a great cyclist might also have suffered a bit from the success of Wiggins and Froome. But at least he has the 'normal and likeable guy' reputation going for him.
He's probably gone under the radar of most Brits, outside of cycling, in terms of his best results/achievements came whilst other Brit riders had larger personalities that dominated the narratives instead, and he just became part of the furniture at Sky/Ineos.