How much rank should you expect to lose when learning a new hero?

I was mainly a Lifeweaver and Ana player, but about two weeks ago I switched to trying to learn Juno. I've expected to lose some rank as I learn the new hero, but I've fallen from Diamond 5 down to Gold 1!

I knew I was going to slip a bit, especially since Diamond 5 was my peak, I probably more frequently fall in the mid-plat range (like Plat 3 or 2), but falling down to Gold feels wonky.

I'm wondering if the rank reset is finally leveling out? because Diamon 5 was the highest I've ever placed when just last season my peak was around Plat 4. I have a feeling numbers were a bit inflated at the beginning of this season.

So, the real question, how much rank should you expect to lose when learning a new hero? I'm at my wits end with Juno, and I'm not sure how much more rank i wanna lose.