reltime() seems broken, just adds literal "<rt>" tag

[magicus]

Describe the bug

I tried to copy the example in the docs, and added:

value_override: '"Changed: {last_changed|reltime()}"'

to my card. However, this does not result in relative times, but instead an output like:

"Changed: <rt>2024-08-26T21:53:45.731Z</rt>

How to reproduce
Add the reltime() function in a template.

Expected behavior
I expected a relative time, like 5 minutes ago.

YAML configuration

type: custom:battery-state-card
title: Battery levels
value_override: '"Changed: {last_changed|reltime()}"'
non_battery_entity: true
default_state_formatting: false
filter:
  include:
    - name: entity_id
      value: '*_last_seen'
unit: null
sort:
  - state

Entity debug data

Dev console errors

Screenshots

Version

I am using the latest version from HACS.

[made-indrayana]

Same here 👋🏼