I don't know if this is just a dumb theory, a red hot take, or something else.
Bi carb isn't working as well anymore (more depth, but guys at top aren't as fast as last year) because they're using it for ALL of their training, and losing some adaptations that come from training through the lactate or whatever the scientific thing is.
So last year they had training adaptations and bi-carb adaptations combined, because they weren't very far removed from "non bi-carb training." But now it's just the bi-carb working. Their body hasn't had to fight through something quite as intense anymore.
OR, maybe guys just aren't as motivated in a non olympic year.
Last year, 5 guys under 1:42, 12 under 1:43. Average of the guys under 1:42 : 1:41.45
This year, 3 guys under 1:42, 17 under 1:43. Average of the guys under 1:42: 1:41.76
Another interesting tidbit, I believe JG said on one of the pods that Brazier does not use bi-carb. correct me if im wrong.