About Splashscreen and PWA

After a while I understood the “splashscreen” in PWA and in Ionic app are two separate concept.
Actually, I had started building an app, but recourse of Google and Apple’s refusal to publish it, I had to switch to a PWA.
The app is a support for local Red Cross subsidiary, but Cupertino and Mountain View are dummy about it, also if this is a pure volunteers’ effort: no COVID related app by independent developers is admitted.
However, we are in hurry, PWA run and we are ready for launch, but…
After the splash of PWA splashscreen disappears as expected, but the screen is white for a few second with a broken-link image; then app become visible. Is that an effect of the splash screen I inserted into the standard app? There is no way ti have the same source for PWA (Firebase hosted) and the (future) standalone apps for Android and iOS?

Ionic info:

Ionic CLI : 6.6.0 (C:\Users\Pietro\AppData\Roaming\npm\node_modules@ionic\cli)
Ionic Framework : @ionic/angular 5.0.7
@angular-devkit/build-angular : 0.803.26
@angular-devkit/schematics : 8.3.26
@angular/cli : 8.3.26
@ionic/angular-toolkit : 2.2.0


Cordova CLI : 9.0.0 (cordova-lib@9.0.1)
Cordova Platforms : android 8.1.0, browser 6.0.0
Cordova Plugins : cordova-plugin-ionic-keyboard 2.2.0, cordova-plugin-ionic-webview 4.2.0, (and 7 other plugins)


cordova-res (update available: 0.13.0) : 0.9.0
native-run (update available: 1.0.0) : 0.3.0


NodeJS : v12.13.1 (C:\Program Files\nodejs\node.exe)
npm : 6.13.2
OS : Windows 10