Background of the issue:
I reordered some ACF Flexible Content blocks and later found out that a link in one block has been duplicated to another content. This is quite bad.
Symptoms:
When reordering ACF Flexible Content blocks, some content gets messed up between blocks that were reordered.
It seems that when block has some empty fields then it will be filled with the block data that they change positions with (in the screenshots, buttons should only exist for white background block; and badges/tags should only exist for bluegrey background block)
