Summary: About the use of vscode! The solution to the + tab invalidation problem
method 1:
Open Settings- -- >---Search emmet --->---Slide to Emmet:Trigger Expansion On Tab option, check it
type emmet
Check the Emmet:Trigger Expansion On Tab option
Method 2:
Just enter html:5 directly
The reason why this shortcut key is invalid is due to the version update of VsCode in June, which can be solved by the above method.