Technical validation on altering atttypmod for numeric column in PostgreSQL

Hi team,
I am evaluating an approach to change the scale of a numeric column from numeric(18,2) to numeric(18,4) in a large table, aiming to avoid the cost of a full table rewrite.
The proposed approach involves directly updating the PostgreSQL system catalog:

UPDATE pg_attribute
SET atttypmod = (18 << 16 | 4) + 4
WHERE attrelid = 'table'::regclass
AND attname = 'column';

Before considering this in practice, I would like to validate a few points:

* Is this approach considered safe from a data integrity perspective?
* Is there a risk of inconsistencies in the internal representation of the numeric type (especially regarding scale)?
* Could this impact indexes, functions, or aggregation operations?
* Is there any official recommendation or prior experience using this approach in production environments?
* Are there additional risks related to rollback, maintenance, or future operations (e.g., dump/restore, upgrades)?

The goal is to determine whether this alternative is viable, or if we should stick with more standard approaches (e.g., shadow column, incremental migration, etc.).
If anyone has experience with a similar scenario, your insights would be appreciated.
Thanks.

Att. Mauricio Martini