Try to close Studio, open the xaml in Notepad++ and look for these details ‘‘V3’.’ Line number ‘191’ and line position ‘465’. Row: 191, Column: 465, and try to change the V3 to V2 → save → try to open the Studio project.
I think you upgraded/downgraded some ui activities or you upgraded recently the UiPath.UIAutomation.Packages to 23.10.9.
You can provide the Studio project archived in a zip file to see if the above solution helped.