Ionic 4 graphics on android 5 and 6 do not work

I have an application developed in ionic 4 that running it on android 6 or 5 looks bad and without the primary colors.

this is my ionic info

Ionic:

   Ionic CLI                     : 5.2.0 (C:\Users\Soporte\AppData\Roaming\npm\node_modules\ionic)
   Ionic Framework               : @ionic/angular 4.6.0
   @angular-devkit/build-angular : 0.13.9
   @angular-devkit/schematics    : 7.3.9
   @angular/cli                  : 7.3.9
   @ionic/angular-toolkit        : 1.5.1

Cordova:

   Cordova CLI       : 9.0.0 (cordova-lib@9.0.1)
   Cordova Platforms : android 8.0.0
   Cordova Plugins   : cordova-plugin-ionic-keyboard 2.1.3, cordova-plugin-ionic-webview 4.1.1, (and 16 other plugins)

Utility:

   cordova-res : 0.5.1
   native-run  : 0.2.7

System:

   NodeJS : v10.16.0 (C:\Program Files\nodejs\node.exe)
   npm    : 6.10.1
   OS     : Windows 7

I can’t think what it could be or how to find the solution. I’d appreciate if you gave me any suggestions

Same here. Anybody knows a solution?