Approximately 2.7 million arrests have been made at the border since Biden became president. Of those, roughly two thirds were immediately removed from the US under Remain in Mexico/Title 42.[1] Many of the remainder were immediately taken into immigration detention, faced removal proceedings, and were themselves eventually removed from the country (as are many who were not initially arrested at the border).[2] It is unclear to me how this constitutes 'de facto open borders'.

[1]https://www.cbsnews.com/news/title-42-immigration-border-bid...

[2]https://www.nytimes.com/2022/09/19/us/politics/us-border-arr...