Formula worked in google sheets but now doesn't work in Microsoft 365 - gSheets Arrayformula

wapc14 so in Excel 365 you don't need or use ARRAYFORMULA, it is just 'built in'.  As for those formulas I think you should be able to just use TAKE(FILTER(),-1) like this:

=if($C2="","",iferror(TAKE(filter($I1:$I$2,$C1:$C$2<>"",0),-1),0)

in addition to no ARRAYFORMULA please note that FILTER also has a different format (i.e. in sheets it takes an array of conditions while in excel all the conditions must be combined into 1 term and then followed by the if_none_found optional parameter)  The TAKE function will specifically take the designated row(s) and in this case choosing -1 is the 1 row starting from the end.

I didn't test it but hope it works or at least gives you understanding how to make it work