Svelte 5: Bogus comments caused by <![><!]>

[Jumaron]

Describe the bug

Today when trying to validate my Website for any HTML errors i used the w3c validator to check for any errors.
To my suprise it showed nearly 1000 errors, 99% of them with the same error:

The html of the page looks like this:

I wonder what could be done since this is both the cause localy on dev and also when deployed.

Reproduction

I have 0 idea when it happens or why.
I guess it happens if you use SSR and a Svelte Element that needs to be client Side fetched or Mounted?
Would be glad if this is not a known issue to help reproduce!!

Logs

No response

System Info

System:
    OS: Windows 11 10.0.22631
    CPU: (12) x64 12th Gen Intel(R) Core(TM) i5-12400F
    Memory: 2.70 GB / 15.85 GB
  Binaries:
    Node: 20.10.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.19 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 10.2.5 - ~\AppData\Roaming\npm\npm.CMD
  Browsers:
    Edge: Chromium (122.0.2365.92)
    Internet Explorer: 11.0.22621.1

Severity

annoyance

[harrisi]

The bogus comment warnings aren't from <!--[-->, it's because what's actually injected is <![> and <!]> (which you can see from the warnings as well). I'm a little surprised these non-standard comments are used. I know it's less noise, but it's not standard. It doesn't seem worth it to save a few bytes and rely on browsers to not be too upset about this.

[Jumaron]

Wait yeah your right i'am just blind.

[Rich-Harris]

The W3C validator is needlessly persnickety — short comments are understood everywhere that matters. That said, the benefit is fairly slight, and in the past we've decided in favour of being compliant, so I'd be open to changing this