blazor after visual studio update throws some strange warnings

after update visual studio to 17.11.3in almoust evert file that i open vs throw some worning as

Severity    Code    Description Project File    Line    Suppression StateWarning (active)    TS1109  (JS) Expression expected.   Miscellaneous   D:\xxx\Components\Core\DialogConfirmComponent.razor__virtual.html__virtual.js   9   

as on screen

is it some .net bug ? or i should do something with it? no idea what it is this _virtual.html_virtual.js ? guess some temp file?

before update there was no such things...?

thanks and regards