I agree. We really need the ability to 'tell' the webmap that it should not automatically try to convert time to (or from) UTC. If I create a label showing DateTime on the layer as part of a dynamic map service, this label is apparently passed without time conversion to the webmap as I want it to do. Viewing a popup for the same feature in the webmap shows another DateTime-value because of the UTC conversion, in some cases it even results in another date. Image here showing an offset of 2 hours around midnight. It's very hard to explain the meaning of this to an end user.
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