I could not replicate the issue on my local installation. Do you have a caching plugin or may have installed one? After doing the updates, always remember to clear all caches (if you are using WP Rocket, WP SuperCache or W3 Total Cache) when updating so that the code from the latest release is always in use. This will help you to avoid any potential errors.
So I created a private page to do a test and the parallax effect is also working. Please check out the secure note.
It could be that your images used in the parallax is smaller. Please edit one of your page with a parallax and upload an image with at least 1200x800 in dimension. You can then compare the result with the smaller and larger image size.
Please let us know how it goes.