Agree with jwilly5.
Eventually figured out why there was some nonsense error that _0.308 -> 0.308.
But bottom line someone can and should be able to use to_char here and because the kata is the way it is that doesn't work.
It's a problem with a lot of the SQL kata on Codewars I'm noticing - just needless little nitpicky errors prevent completion

kata hint != kata suggestion

They are essentially grouping by the first day in each month. When in reality grouping by month could have just been 2020-01 (Jan 2020), 2020-02 (Feb 2020), 2020-03 (Mar 2020) and so on, they opted to adding a '-01' to each grouping. It results in the same output by month but is not necessarily needed in my opinion.

Not sure why everyone is hating on this Kata, everything worked out as expected. The issues previously noted by people did not appear to still be issues.

This is now defined in the problem statement near the end.

I have everything done except this, not sure what other function to use...I don't want to have to manually extract the month number from the date but might have to...

I am having this am having this same problem, did you end up finding out why?