Sheetgo adds a sheet tab on your chosen destination spreadsheet that holds your source data. This tab is managed by Sheetgo and thus is locked (protected) and underlined green to avoid manual modification.
Every time the associated connection is updated, the destination sheet tab will be erased and repopulated with the latest source data.
Therefore, never make changes to the destination sheet tab as all your modifications will get lost upon the next connection update.
In order to annotate and leave notes on the destination sheet, you can create a new sheet next to the sheet which is managed by Sheetgo (the green underlined one). Then use the ARRAYFORMULA or Query to bring over the data from the original destination sheet to mirror it.
Remember: Sheets created by Sheetgo are underlined green and usually locked to prevent you from doing any manual changes. Because this sheet is managed by us.