Test

{

 "$schema": "https://vega.github.io/schema/vega/v5.json",
 "width": 800,
 "height": 300,
 "padding": 5,
 "data": [
   {
     "name": "membres",
     "values": [
       {"label": "jakub", "nom": "Jakub Larsen-Li", "membre_start": "2021-08-05", "membre_end": "2021-09-02", "status": "❌"},
       {"label": "josé", "nom": "José Fripougnon", "membre_start": "2021-08-05", "membre_end": "2021-08-24", "status": "❌"},
       {"label": "josé", "nom": "José Fripougnon", "membre_start": "2021-08-31", "membre_end": "2021-09-02", "status": "❌"},
       {"label": "taylor", "nom": "Taylor Newton", "membre_start": "2021-08-05", "membre_end": "2021-08-31", "status": "🚪"},
       {"label": "benito", "nom": "Benito Folliero", "membre_start": "2021-08-07", "membre_end": "2021-09-02", "status": "❌"},
       {"label": "charlie", "nom": "Charlie Lucheco", "membre_start": "2021-08-07", "membre_end": "2021-08-22", "status": "💢"},
       {"label": "jon", "nom": "Jon  « Kira » Kino", "membre_start": "2021-08-26", "membre_end": "2021-08-30", "status": "💢"}
     ],
     "transform": [
       {
         "type": "formula",
         "as": "membre_end",
         "expr": "datum.membre_end || now()"
       }
     ],
     "format": {
       "parse": {
         "membre_start": "date",
         "membre_end": "date"
       }
     }
   },
   {
     "name": "seconds",
     "values": [
       {"label": "josé", "second_start": "2021-08-05", "second_end": "2021-08-24"},
       {"label": "taylor", "second_start": "2021-08-24", "second_end": "2021-08-31"}
     ],
     "transform": [
       {
         "type": "formula",
         "as": "second_end",
         "expr": "datum.second_end || now()"
       }
     ],
     "format": {
       "parse": {
         "second_start": "date",
         "second_end": "date"
       }
     }
   },
   {
     "name": "chefs",
     "values": [
       {"label": "jakub", "chef_start": "2021-08-05", "chef_end": "2021-09-02"}
     ],
     "transform": [
       {
         "type": "formula",
         "as": "chef_end",
         "expr": "datum.chef_end || now()"
       }
     ],
     "format": {
       "parse": {
         "chef_start": "date",
         "chef_end": "date"
       }
     }
   },
   {
     "name": "events",
     "values": [
       {"name": "05/08 - Création du groupe", "date": "2021-08-05", "y": -20},
       {"name": "02/09 - Dissolution du groupe", "date": "2021-09-02", "y": -20}
     ],
     "format": {
       "parse": {
         "date": "date"
       }
     }
   }
 ]

}