Non standard hub bearing? I need to replace a hub bearing. On it, I can Read ZPL (manufacturer I guess) and 6200RS. 6200 seems to be a standard for (inner diameter x outer diameter x width) 10 x 30 x 9mm. But when I measure, I get 12.65 x 28.75 x 9.00 mm.

My measurement tool is accurate, I've tripled-checked it.

It is not because the bearing is worn out on the outside and inside, since the bearing fits perfectly on the axis and the hub.

I bought the bike second hand, it was imported from Tokyo, I live in France.

How do I replace the piece? I cannot find any bearing with similar measurements and a standard 6200 surely won't fit.
Sounds like the bearing has the wrong dust shield.  Sizing lines up closer to an imperial(inches) sizing, 1/2"x1 1/8" x 3/8"ish.  The inside and outside diameters are close, the width is less important than the ID and OD as you typically have a preload adjustment on the axle.  Try a 1616-2RS (9.5mm wide) or a R8-2RS (8mm) bearing.

Alternatively, If the bearing is simply feeling rough, you can remove the dust cover with a knife, clean out the bearing with alcohol and repack with a marine grade grease.  This may improve the smoothness if the races are not too pitted/corroded and add a bit more life to the bearing.