### Symfony version(s) affected Tested and reproduced on 4.4 and 5.3 ### Description In case the first character of the string is ampersand ```&```, then two equivalent syntax of YAML-Collections produce different output for the same values. ### How to reproduce Add YAML parameters like: ``` parameters: # Correct values in console output -> ["&string1","&string2","&string3"] collection_output_correct: - '&string1' - "&string2" - !!str &string3 # Wrong values in console output -> ["","","",""] collection_output_wrong: ['&string1', "&string2", !!str &string3, &string4 ] ``` Run ```bin/console debug:container --parameters``` and compare output for 'collection_output_correct' and 'collection_output_wrong' parameters. ### Possible Solution _No response_ ### Additional Context _No response_