Now it appears that every attempt to buy Minecraft Java Edition, whether via Microsoft, Minecraft.net or accounts.mojang.com results in a redirect to the Amazon Purchase page.
 
When purchase is attempted the following error is displayed:
 
Some items are no longer available
We're sorry. Some items became unavailable after you added them to your shopping cart. Click here to return to the product detail page and try another seller.
 
 
It seems that it's now impossible to buy Minecraft Java Edition.
 
I live in Australia.