The fix should be part of the latest release.

The script adding an attachment should look like this

const jsreport = require('jsreport-proxy')
async function afterRender(req, res) {
  res.content = await jsreport.pdfUtils.addAttachment(res.content, Buffer.from('hello'), 
    name: 'my attachment'
  }, {
    pdfAccessibility: {
      enabled: true
    }
  })     
  res.content = await jsreport.pdfUtils.postprocess(res.content, {
    pdfAccessibility: {
      pdfUA: true,
      enabled: true
    }
  }) 
}

Please share the minimal workspace that replicates the issue.
You can confidentially email it to me jan.blaha@jsreport.net

Thank you for the topic. I will check it out and come back here.

Thank you, I can reproduce it now.
We will fix it in the upcoming release.

Are you able to email me your workspace export to jan.blaha@jsreport.net?
Or please try to isolate the problem by removing your folders to find out which entity is the cause.

It works for me in latest as well as in the 4.10.1.

Please share details when it happens.

Im not sure what you mean...
If you want field value to have black text, just use
color='#000000'

Write your own helper that will evaluate handlebars code
Something like this

function evaluate() {
    return Handlebars.compile('{{#if true}}hello{{else}}nothing{{/if}}')(this)
}

Try value attribute

 {{{pdfFormField name='firstName' value='hello world' color='#FF0000' required=true type='text' width='200px' height='20px'}}}

I apologize if I missed something. It’s been a long time since I last worked with .NET...
I don't see the jsreport.Client would be dependent on the System.Text.RegularExpressions

Could you check the following?

dotnet list package --include-transitive
dotnet list package --vulnerable --include-transitive