DRRPhoto2024
From what you've written, I'm assuming that this budget spreadsheet is a new one, begun in December, set up for January to copy from December showing increases and decreases. You're having difficulty now with the February one. If that is right, if in particular it's correct to have understood this as an early effort at budget tracking, may I make a suggestion?
Re-design.
Don't have a separate tab for every month. Keep all data in a single database. Excel is really good at developing summaries of such things as expenses by category by month, working from a single transactional database.
You are doing this in a way that would have made sense if you were keeping records on paper. But you're not keeping records on paper. You're using Excel; but you're not using Excel well.
Would you be willing to share a copy of the workbook you have so that I (or some of the other Excel experts here) could take a look at it and make suggestions as to how it could be improved to take more complete advantage of Excel? Post a copy of the workbook on OneDrive or GoogleDrive, and paste a link here that grants access to it.