is this relevant for ALL moves and move lines? 🤔
A change on so line section might have a big perf impact. no?

is this relevant for ALL moves and move lines?

The fields are added on stock.move and stock.move.line, so the columns exist for all records, but they’ll only be filled (non-null) for moves/move lines that come from a sale order line (sale_line_id) and where that sale line has a section (section_id). For other moves (inventory, manufacturing, purchase, etc.) it stays empty.

A change on so line section might have a big perf impact. no?

It can, yes.
Because sale_section_id / sale_section_name are stored related fields, if you change the section on a sale order line, Odoo may need to recompute + write the stored value on all dependent records:

• all stock.move linked to that sale line (sale_line_id)
• and then all stock.move.line linked to those moves
  So if someone bulk-updates sections on confirmed orders with lots of moves/move lines, that can trigger a large cascade of writes (and be noticeable on big DBs).
  If section changes are rare, the impact is usually limited.

Another option:
Make sale_section_* non-stored computed/related fields.

• Pros: changing the section won’t trigger mass writes on moves/move lines.
• Cons: you generally lose efficient search/group-by on those fields (or it becomes slower because it computes on the fly).