Hope you are doing well and and sorry for the trouble.
- Is this a behavior with a particular PDF file or with all the PDFs? Please try with a different PDF file and check.
- What is the version of the Adobe Acrobat Reader DC you are using? To check the version go to Help > About Acrobat and make sure you have the latest version 21.05.20058 installed and reboot the computer once. Go to Help > Check for Updates.