What each path shares with your bank data
Direct Import: YNAB’s built-in connection (Plaid in European markets YNAB supports). No BudgetSyncer involved. Prefer it when the bank stays connected.
BudgetSyncer: PSD2 consent via Enable Banking, read-only transaction access for sync into YNAB via OAuth. Passwords are not stored by BudgetSyncer. See does BudgetSyncer store bank passwords and is BudgetSyncer safe for YNAB.
CSV/OFX: you download files from online banking and upload them. No standing open banking token with BudgetSyncer, but the file often contains full history and pending rows you must reconcile by hand.

