Unexpected NETSDK1210 after removing TFM

[MihaZupan]

Describe the bug

When using IsAotCompatible in a library that targets multiple TFMs, the NETSDK1210 warning appears after removing a TFM.

IsAotCompatible and EnableAotAnalyzer are not supported for the target framework. Consider multi-targeting to a supported framework to enable ahead-of-time compilation analysis, and set IsAotCompatible only for the supported frameworks. For example:
<IsAotCompatible Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net7.0'))">true</IsAotCompatible>

To Reproduce

• Create an empty class library project
• Set the TFMs and mark as AOT compatible

  <TargetFrameworks>net6.0;net7.0;net8.0</TargetFrameworks>
  <IsAotCompatible>true</IsAotCompatible>

• Build and observe no warnings
• Remove the 7.0 target: <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
• Build and observe a NETSDK1210 warning

Further technical details

• SDK 9.0.100-preview.3.24204.13

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While we can workaround the issue as hinted in the warning message, is it expected that this would show up after removing the 7.0 TFM, even though you still have 8.0?