field_sorting_liquid

{% capture tuples %}
{{ subscriber.field_a }},field_a|
{{ subscriber.field_b }},field_b|
{{ subscriber.field_c }},field_c|
{{ subscriber.field_d }},field_d
{% endcapture %}

{% assign sorted_tuples = tuples | split: "|" | sort | reverse %}
{% for tuple in sorted_tuples %}
{% assign tuple_array = tuple | split: "," %}
{{ tuple_array[1] }}: {{ tuple_array[0] }}
{% endfor %}