Agregation ('+') in expression fill-color does not render proper color

I have this style for my fill layer

"fill-color": [
  "step",
  ["to-number", ["get","total"]],
    "#d1eeea",
    2, "#68abb8",
    4, "#2a5674"
]

Works well values are filled with the right colors,

Now instead of the TOTAL I want to agregate the 6 variables that make the total. (each is between 0 and 1)

Like this :

"fill-color": [
 "step",
              [
                "+",
                ["to-number", ["get","acp_sociale"]],
                ["to-number", ["get", "acp_econo"]],
                ["to-number", ["get", "cp_enviro"]],
                ["to-number", ["get", "acp_securite"]],
                ["to-number", ["get", "acp_proximite"]],
                ["to-number", ["get", "acp_cultsportloisir"]]
              ]
]

Issue :

The hexagons are filled with bad colors e.g : The hex should be in the intermediate color not in the highest ranked one.

Any hint why this would happen ?

Thank you all, have a pleasant day

No source file, test, or entry point is named. Start by reproducing the two fill-color expressions from the report in mapbox-gl-js and compare the aggregated expression's numeric result with the step thresholds and rendered colors. Done means identifying whether the expression evaluates incorrectly or the reported thresholds are mismatched, then recording the finding in a focused regression test or documentation update.