This is no longer accept since the 10.4.12
But if you already have a table with similar schema, is still working.
I check in the doc / release note and the only possibly related entry I was able to find are:
MDEV-21249 MariaDB 10.3.10 When referring to bigint to generate timestamp data in the virtual generated column, the value of the generated column does not change when the time zone changes
As a side note also the `
` no longer work so
create table newTable like tableWithVirtColum;
Error in query (1901): Function or expression 'from_unixtime()' cannot be used in the GENERATED ALWAYS AS clause of `dateCET`