Test Failure: System.Text.Tests.TranscodingStreamTests.CanRead_DelegatesToInnerStream

## Build Information
Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1521506
Build error leg or test failing: System.Text.Tests.TranscodingStreamTests.CanRead_DelegatesToInnerStream
```
Starting: System.Text.Encoding.Tests (parallel test collections = on [8 threads], stop on fail = off)
System.Text.Tests.TranscodingStreamTests.CanRead_DelegatesToInnerStream(expectedCanRead: True) [FAIL]
System.NullReferenceException : Object reference not set to an instance of an object.
```

## Error Message

Fill the error message using [step by step known issues guidance](https://github.com/dotnet/arcade/blob/main/Documentation/Build%20Analysis/KnownIssueJsonStepByStep.md).

```json
{
"ErrorMessage": "System.Text.Tests.TranscodingStreamTests.CanRead_DelegatesToInnerStream(expectedCanRead: True) [FAIL]",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
```

### Known issue validation
**Build: :mag_right:** https://dev.azure.com/dnceng-public/public/_build/results?buildId=1521506
**Error message validated:** `[System.Text.Tests.TranscodingStreamTests.CanRead_DelegatesToInnerStream(expectedCanRead: True) [FAIL]`]
**Result validation:** :white_check_mark: Known issue matched with the provided build.
**Validation performed at:** 7/23/2026 2:50:15 PM UTC

### Report
#### Summary
|24-Hour Hit Count|7-Day Hit Count|1-Month Count|
|---|---|---|
|0|0|0|