Error code 12019054 is indicative of the pictures you're sending to TikTok Shop are of the wrong aspect ratio.
Overview
TikTok Shop recently tried to enact a policy where any images uploaded to TikTok Shop had to be in a perfectly square aspect ratio. They have since repealed this policy and are instead adjusting pictures to be square on their end. However, if you uploaded any products to TikTok Shop via SKU IQ during the brief time period that this policy was in place at TikTok Shop, you may be running into error code 12019054.
The Error Message
Tiktok Error {"code":12019054,"data":null,"message":"Incorrect sale information image tos-useast5-i-omjb5zjo8w-tx/3accb6e084354c4698c0bbf93d767a02 aspect ratio"
How Do You Fix it?
This is what we call a soft error message, meaning it doesn't actually impact uploading information to these already existing products. So you can actually ignore this one as any data changes coming from Shopify will still push to TikTok Shop.
However, if you would like to fix it, you will need to delete the product from TikTok Shop. You can do so by using the "where" toggles on the product detail page for that item on SKU IQ. Toggling the TikTok Shop toggle to "OFF" will delete the item from TikTok Shop. (You may also want to double check on seller center that the item is gone. If it's not, delete it there too!)
There is a small problem in doing this: any videos that you have had tagged with those products previously will no longer have a tagged product. TikTok currently does not allow you to edit existing videos, so you will not be able to re-tag the videos and you may lose valuable data in regards to trends and views.
Since this is a soft error, you can of course, choose to simply ignore it as "noise" on the sync events on SKU IQ.