I can run 10 km, MTB 30 km, fat level at 18% and still have prediabetes.

Sometimes is just a bad roll on the genes.

I know that by modern standards, 18% is better than average, but it's also still pretty fat for men. Men should strive for a 10-14% range. <10% is associated with hormone (specifically testosterone) deficiency, and >14% is both aesthetically disgusting, and bad for metabolic health.

Try losing more fat, to the 12% level, then check your biomarkers again.

Photoprism is ok, but the AI features of immich are far superior

What value are you finding in the AI?