100km is such a long distance, at your current pace you'll probably get there in the time you have left in the year. I would be worried about injury if I attempted such a distance but I figure you have that covered. Every time I go for a 30mins jog the calf pain is unbearable if I don't space the cardio days out. I keep seeing TikTok influencers say stretching and mobility exercise helps but I don't see how.

Have you tried any of that since you started working on this goal?