Two timezone in the same column from the same source

Hi guys, 

I have some datas that are in YYYY-MM-DD, and some in DD/MM/YYYY, in the same column (the latest gives me an error that I can't transform in text, because the error comes at the first step). The funniest is that the dates that doesn't show an error are all wrong (it even gives me futur dates).

Anyone has any idea of how I can handle this?

Thanks!

error = 20/01/2020 11:46