Hope you are doing well.
Is it possible for you to share a video recording of this behavior for better understanding?
There's likely a chance that the document you are working with doesn't contain the real text. It's a scanned file. So the highlighting doesn't have symmetry.
Meanwhile, try these steps to see if it makes the performance any better:
1- Open Acrobat/Reader> help>check for an update
To download the patch manually, more information about this release is here: Release Notes | Adobe Acrobat, Reader
Navigate to Acrobat>Edit>Preferences>Security (Enhanced)>disable "Protected View" and "Enhanced Security">OK>close and reopen Acrobat.
Note: these changes are only for testing purposes. Once tested, please change it back to the previous setting.