I do not see this as one day off but as 1 month off
Database format looks like yyyy-MM-dd HH:mm:ss
Your Wappler input is MM-dd-yyyy HH:mm:ss
So you have 2 problems here, 1 is that your datetime picker in Wappler is set to format as per your locale, so wherever you are, while your server database is in a more normal, or different locale format.
2. is that your time seems to be 12 hours off.
So you just chose the worst dates as well as times you could have for your testing, as the midday went 12 hours off and added a full day by turning to midnight, and your month and day are transposed.
Try test with a date that is out of range for the database to transpose, so try something like
20th May 2021 at 3:00 PM and I assume it is going to give an error inserting the record because it will try to use 20 as the month which is impossible.
Once you ascertain if that is in fact whats going wrong, then look at either your server mysql to see what timezone that is set to, and adjust if needed, else if that is correct, then adjust the Wappler picker to account for it.
Try mess with the Format and times UTC options to get it working as expected
If you dateformat to your user has to be displayed as MM-dd-yyyy HH:mm:ss and you have no control over your server, then you can also leave both as they are and adjust on the Wappler Database Insert/Update server action. with something like
{{$_POST.removaldate.formatDate('dd-MM-yyyy HH:mm:ss')}}
Keep in mind there are other formatters for date adjustment before the sql insert step like
.toUTCTime()
.toLocalTime()
.dateAdd('days', -5)
.formatDate('dd-MM-yyyy HH:mm:ss')