Dynamax Adventures - shiny odds connected to story completion?

There is a lot of info out there about shiny odds in the dynamax adventures.

Screen Rant, wrote:

At this time, if the player has all four Pokémon slots filled, the chances of a shiny Pokémon without a shiny charm is 4 in 300, or 1 in 75. However, with the Shiny Charm equipped, the odds are an incredible 4 in 100, meaning 1 in every 25 Pokémon could be shiny.

I’ve probably done at least 50 dynamax adventures with the shiny charm, but I’ve yet to come across any shinies.

Are the shiny odds in the dynamax adventures connected to story completion? There are some parts of the story that I have not completed – I’m just wondering if this is holding my odds back or not?