HTML Mail - Strikethrough Text Shown As Subscript

Not sure if this was the case prior to the most recent update, but I just noticed today that text struck through with ~~ is shown as (what looks like) a subscript. I’m including a couple of screenshots. If it helps, I am using the Markdown Mail action.

The Markdown:

The HTML Mail Message:

Maybe this is related to Strikethrough Not Shown in Preview?