Date extraction and conversion

Hello everyone!

I was facing a lot of issue regarding DATE type on my Dashaboard and wasn't understanding why PowerBi was not returning to me the correct Date value, so I've made a test table to check how it was working with Date values and the same strange unkown issue happened. Follow below what I did (and really expect that some of you could explain to me why it happens):

I've just used TODAY(), MONTH(), FORMAT() expressions and some simple extractions from a Date column. My date settings are Brazilian Portuguese, so our Date pattern here is "dd-mm-yyyy".

I've created one table called TestDate;
First column: Today = TODAY()
Result: 01/06/2021 00:00:00

Second column: Month_Today = MONTH(TODAY())

Result: 6

Third column: Format_Month_Today = FORMAT(MONTH(TODAY()),"dd-mmmm-yyyy")

Result: 05-janeiro-1900

 

Fourth column: ExtractFromTable = 'TestDate'[Today].[Month]

Result: June

 

Fifth column: Format_From_extracted = FORMAT('TestDate'[Today].[Month], "mmm")

Result: June

My doubts regarding this are:
1. Why the third column show this date?
2. Why the fifth column is showing "June" instead of "Jun" as requested on FORMAT?

Thanks!