Rails: 7.2.1
Haml: 6.3.0

controller.rb

def index
    respond_to do |format|
      format.html
      format.turbo_stream
    end
end

index.turbo_stream.haml

Test
= if true
  Test

/index.turbo_stream returns

Test
Test
Test
Test

If I change index.turbo_stream.haml to if false everything works

index.turbo_stream.haml

Test
= if false
  Test

/index.turbo_stream returns

Test

I already changed to .erb instead of .haml and everything works as expected, I assume it's a haml issue.