Niagara Mesh Renderer causes GPU hang on IOS 13.4.1

1. Create a Niagara with mesh renderer (a sample project [Link Removed]
2. Build an IOS IPA.
3. Install it on an Iphone in IOS 13.4. (It couldn't repro it in IOS 14 and above devices)
4. It crashes because of GPU hang.

A licensee reported that it would cause GPU hang on IOS 13.4 with Niagara mesh renderer, it couldn't repro on IOS 14 and above and couldn't test with UE5.0 because the lowest IOS version supported is IOS 14 in UE5.0.

The licensee did two changes as a workaround in shaders, and both of them are needed.
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