QOpenGLTexture::hasFeature(QOpenGLTexture::ImmutableStorage) returns false on ANGLE OpenGL implementation even though it has the GL_EXT_texture_storage extension.

The problem seems to be this test on line 3476 of Src/qtbase/src/gui/opengl/qopengltexture.cpp

case ImmutableStorage:
supported = (f.version() >= qMakePair(3, 0) || ctx->hasExtension(QByteArrayLiteral("EXT_texture_storage")))
&& !(renderer && strstr(renderer, "Mali")); // do not use on Mali: QTBUG-45106
break;

The test should be for "GL_EXT_texture_storage", not "EXT_texture_storage".