Missing suggestions for "backdrop-filter" in CSS

Type: Bug

Enter the backdrop-filter property in a CSS file, but no suggestions are triggered.

However, filter property works fine.

values listed in the mdn.
https://developer.mozilla.org/en-US/docs/Web/CSS/backdrop-filter

Values

none | <filter-function-list>

Formal syntax

backdrop-filter = 
  none                 |
  <filter-value-list>  

<filter-value-list> = 
  [ <filter-function> | <url> ]+  

<filter-function> = 
  <blur()>         |
  <brightness()>   |
  <contrast()>     |
  <drop-shadow()>  |
  <grayscale()>    |
  <hue-rotate()>   |
  <invert()>       |
  <opacity()>      |
  <sepia()>        |
  <saturate()>     

<url> = 
  url( <string> <url-modifier>* )  |
  src( <string> <url-modifier>* )  

<blur()> = 
  blur( <length>? )  

<brightness()> = 
  brightness( [ <number> | <percentage> ]? )  

<contrast()> = 
  contrast( [ <number> | <percentage> ]? )  

<drop-shadow()> = 
  drop-shadow( [ <color>? && <length>{2,3} ] )  

<grayscale()> = 
  grayscale( [ <number> | <percentage> ]? )  

<hue-rotate()> = 
  hue-rotate( [ <angle> | <zero> ]? )  

<invert()> = 
  invert( [ <number> | <percentage> ]? )  

<opacity()> = 
  opacity( [ <number> | <percentage> ]? )  

<sepia()> = 
  sepia( [ <number> | <percentage> ]? )  

<saturate()> = 
  saturate( [ <number> | <percentage> ]? )  

One more thing

My last issue #55 is fixed.
However, if you proceed to this step as shown in the image below,

then press TAB key, the suggestion list will NOT show automatically unless you press the shortcut (default is Ctrl + Space) manually.

But if you spell the white-space completely and type a colon, it will work again.

VS Code version: Code 1.74.2 (e8a3071ea4344d9d48ef8a4df2c097372b0c5161, 2022-12-20T10:29:14.590Z)
OS version: Windows_NT x64 10.0.22621
Modes:
Sandboxed: No

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fim-prod:30623723
vscsbc:30628655

Start by inspecting the repository's custom data documentation and samples, then reproduce the issue by entering backdrop-filter in a CSS file in VS Code. The work is done when value suggestions appear for the property and suggestions also appear automatically after completing a property through the Tab key.