My character is on PS5. How can I trade on PC if I can't buy premium stash tabs?

So I own the game on PS5, Xbox, PC. I have a key for all 3.

I understand MTX from PC and Xbox does not work with PS5.

I have premium tabs on PS5. I purchased the game on PC/Steam so I could go on and trade and sell items.

When you create a character it goes to a platform. So you have to pick your account name before you make a character.

For example my PS5 account is Idle-Race#9384
I also have a PC which is IdleRace#6145, and Idlerace#8467 which is xbox

So when I go to play my character I have to select Idle-Race#9384 since this is a playstation account I can play it on PC version but I can not buy any MTX.

My issue is I want to play my character on PC version I am ok with buying stash tabs on each platform I play on but the game does now allow me to.

My issue is that I can not buy any MTX on PC while being on my playstation account. The character I create is locked to playstation.

This is a error from GGG. My character should not be locked to a platform. I should have this character on PC, Xbox, and PS5.

The problem this makes is you ony can buy mtx for the character on one platform.