Inconsistent use of "yesterday"

Using relative-time-element v4.4.5.

I am in a UTC-5 time zone. The current time for me is April 30 1:53PM (2025-04-30 18:53 UTC).

I've set up a test page at https://greasyfork.org/en/relative_date_test to show the last 48 hours of <relative-time>. Here is what I see:

• 0 hours ago shows "now", no issue.
• 1 - 13 hours ago (Apr 30 for me) - shows as "x hours ago", no issue.
• 14 - 20 hours ago (Apr 29 for me) - shows as "x hours ago", could also show as "yesterday", but that's fine.
• 21 - 35 hours ago (Apr 29 for me) - shows as "yesterday", no issue.
• 36 - 37 hours ago (Apr 29 for me) - shows as "2 days ago".
• 38 - 48 hours ago (Apr 28 for me) - shows as "2 days ago", no issue.

36 and 37 hours ago for me is Apr 29 12:53AM and 1:53AM, which is still "yesterday", not "2 days ago". Especially weird that then Apr 29 2:53AM is "yesterday".

I imagine that maybe "1.5 days ago" is getting rounded up to "2 days ago", but "yesterday" is a concept of calendar dates and not a number of hours, so there's no reason to stop using that term until it's no longer 1 calendar day ago.

Commencez par la page relative_date_test liée et reproduisez le comportement signalé avec relative-time-element v4.4.5 dans l’exemple UTC-5. Suivez le point d’entrée du rendu de relative-time et vérifiez que les horodatages vieux de 36 à 37 heures affichent toujours « yesterday » lorsqu’ils correspondent à la date calendaire locale précédente, tandis que les horodatages datant de deux dates calendaires affichent « 2 days ago ».