Check this article: gparted block size warning
WARNING: the command shown at the link above will destroy all data on the given device - the same goes for the command below.
It does mention to the same warning message. When a USB stick was used to install Ubuntu, the creation of the booteable media could change the block size of the USB device.
The solution, according to the article author is to run the following command, replacing
<device_path>, with your device path, for example
sudo dd if=/dev/zero of=<device_path> bs=2048 count=1 # this will destroy all data on the given device