For consistency we could enforce a standard iso behavior for the week function by default.

For mysql there is the weekofyear function that matches the iso behavior.
hsql uses iso by default
oracle should use iw, not ww

However:
h2 uses the locale (the current teiid behavior)
sqlserver/sybase you can use SET DATEFIRST to move the first day of the week to monday, but the return values are still not fully iso.

And there are still several others to verify