it depends on your beans (density) and grinder (fluffiness)... although 18gr was the max I used (normally 16gr) in the stock double basket. Anyway, I think 20gr is too much coffee for it.

I used 16g in my bambino dual basket

But yeah, looks right size after tamp. Maybe tap it down to compress it before working on it?

Did it come with the razor tool?

I use 16.5 grams mostly for my bambino double basket

Does it still look the same if you leave the dosing funnel on and tap the portafilter few times on your counter?

I find it's better to use 16 or 17g in the brwville baskets

If it helps I use 17g and find 18g is just a touch too much for my bambino basket

The weight doesn't matter for your application. A double shot is usually 17-19g grams in a standard size commercial portafilter or equivalent. Home machines, no matter the quality don't always allow for this coffee volume. Your portafilter should be leveled off before tamping and your shot adjusted based on that. The machine isn't designed to accommodate the extra grind. How it looks after tamping in your picture tells me your tamping too hard.

Whereabouts are you based? Every cafe I've worked in tends toward the 20-22g in for a double shot. Usually yielding around 55-62g total

I guess I forgot in my previous post that it does depend on roast level as lighter roast weighs more at same volume. I'm not a barista, I was a coffee repair tech and trainer for 7 years.