When tagging a message, it would be helpful if in addition to the little colored tag in the bottom right-hand corner, if the message in the message list could be outlined in the same red/green or other color so it would be easier to locate.
I just want to add that this applies to the cards view, not to the classical list view. And yes, it would really be a big improvement. The little color tag icon is almost unnoticeable. It's useful if there are multiple tags applied. But the color of the first one should also be applied to the border.
I finally figured out to set it back to how it was before the newest update- If the table preview looks weird when opening Thunderbird, click on the settings icon in the bottom left, then "appearance" and under Message List, click on the "table view". When u close that window again, you'll see the message list back to how it was.