Getting script errors in Unity 2021.1.6f1 that are not appearing in 2021.2.0a13 or previous versions

Hi,

I get a new set of errors after upgrading to Unity 2021.1.6f1 in URP project, related to variables and functions protection level.

I attach an image for reference, this was not happening in Unity 2019.4 latest version

Any help would be greatly appreciated, could this be a bug in Unity or is some new ways in code that i should be aware of ?

Thanks in advance.

Note that i have solved the errors by declare all required as public, but wondering if this is the right way or there is something else i miss.

For reference, the full code of the Temporal AA for URP is included in the below github.
https://github.com/sienaiwun/TAA_Unity_URP