parse_dates migration processor inconcistent timezone handling

Problem/Motivation

It seems like the end time and "until" times are going through some extra timezone processing that the start time does not go through.

Steps to reproduce

On a site with America/New_York site timezone, run this migration:

id: school_calendars
label: School Calendars
migration_group: calendar
migration_tags:
  - node
source:
  plugin: embedded_data
  data_rows:
    -
      title: "My Event"
      time:
        -
          value: "2024-04-12T00:00:00-04:00"
          value2: "2024-04-15T23:59:59-04:00"
  ids:
    title:
      type: string
process:
  type:
    plugin: default_value
    default_value: event
  title: title
  field_when:
    - plugin: single_value
      source: time
    - plugin: parse_dates
      entity_type: node
      bundle: event
destination:
  plugin: 'entity:node'

What I expect:
Fri, Apr 12 2024, All day
Sat, Apr 13 2024, All day
Sun, Apr 14 2024, All day
Mon, Apr 15 2024, All day

What I get:
Fri, Apr 12 2024, 12am - 7:59pm
Sat, Apr 13 2024, 12am - 7:59pm
Sun, Apr 14 2024, 12am - 7:59pm
Mon, Apr 15 2024, 12am - 7:59pm
Tue, Apr 16 2024, 12am - 7:59pm

Proposed resolution

Looks like ParseDates.php line 373 is calculating a timezone offset that is then manually applied in the next line. I am not sure what the purpose of that is, but it seems to be causing this issue.

Remaining tasks

User interface changes

API changes

Data model changes