I apologize for the issue you are experiencing. With the recent addition of the “Duration” field, any new or updated formula fields that return a date interval will now use the latest “Duration” format, which reports the number of seconds within the interval instead of a string.
Would it be a problem to convert it from the number of seconds?
Otherwise, what do you think of a new formula to return the new duration field values in the old format? So if you have something like field('duration field'), the result will still be a number, but if you do date_interval_format(field('duration field')), the result will be what it was before so something like “Days”: “157 days 16:40:37.249298”. What do you think?