For anyone looking for an answer - it is very prosaic and I was able to identify the problem.

The problem is empty line in the middle of the query, which is interpreted as end of query by DBeaver.

So easy fix is:

• learn to write queries without them.

Harder fix:

• set interpretation rules so empty line is not interpreted as end of query (behavior is similar to “;”)

Viva la long night, but finally I know why this was happening.