Recently Shopify started rolling out a new update to the theme preview functionality and after this update the Preview buttons in the Online Store Theme Library are no longer anchor tags, but button tags that redirect to the associated theme preview on click.
The link has also changed from the simple xxxx.myshopify.com?preview_theme_id=XXXXXXX format to include some hash and a preview token, which make it unique and impossible to manually replicate. Furthermore, the preview expiration duration is reduced from 2 weeks to just 2 days.
While there might be some good reasons for this update, it causes problems with the QA phase of theme development process. Whether it is a human that’s going to do the QA, or an automated workflow, 2 days is too short of a timeframe, especially near weekends or holidays and will require re-creation of the preview link multiple times, resulting in lost time and a lot of confusion between the developers and the clients. Even a duration of 2 weeks was sometimes not enough, and the URL from anchor tag was very handy at those times.
So, I hope the Shopify team will consider the disrupting nature of this update and revert the Preview button and URL back to its original form.
Thanks!