Tamron has announced that some of their new 70–180mm F2.8 lenses may suffer from a floating system issue.
Here’s their statement:
We would like to announce that we found the performance of the floating system which corrects the field curvature may be insufficient (*) in a part of our 70-180mm F/2.8 Di III VXD (Model A056) products for SONY mirrorless cameras.
For affected products, we will inspect them and either readjust or exchange them.
How to check affected products
To confirm if your product is one of those affected, please click the Check Serial Number button below and enter the serial number of your lens. If your lens is affected, please follow the instructions provided. If your lens is not affected, you may continue to use it without concern.
The full announcement can be found here.
I have this lens myself and luckily it’s not affected by this issue.