The package in question is a custom package - and custom packages are unsupported - it is not that some is supported and others not - they are equally unsupported.
Even if they can be build and maintained by yay and pamac - the result is unsupported.
- Never maintain repo packages and custom packages in the same run
- Remove custom package(s) when they interfere with the sync
After you have succesfully synced your system - you rebuild the package(s) in question.
Then you remove every, every AUR package tha confilicts
That deprives the members trying to help from possibly important information.