Then you have to look around where you can find a better source. In german and hard to read: Quellen für historische Kurse
If you can’t find a source with values from borsa italiana you can use other sources from other exchanges. The values are then not exactly the same, but the direction is correct.
For example
US912810TV08 (Exchange Stuttgart per onvista)
https://api.onvista.de/api/v1/instruments/BOND/258813091/eod_history?idNotation=441762676&range=M1&startDate={TODAY:yyyy-MM-dd:-P1M}
$.datetimeLast[*]
$.last[*]
{TODAY:yyyy-MM-dd:-P1M} is a makro which works in PP, not in a browser.
If you want to see the response in a browser use
https://api.onvista.de/api/v1/instruments/BOND/258813091/eod_history?idNotation=441762676&range=M1&startDate=2025-03-13
GB00B1VWPJ53
https://api.onvista.de/api/v1/instruments/BOND/16975292/eod_history?idNotation=73097102&range=M1&startDate={TODAY:yyyy-MM-dd:-P1M}
$.datetimeLast[*]
$.last[*]