A delegation warning is a production incident on a delay.

Why this rule exists

Non-delegable queries silently truncate at the row limit. Dev data is small, so everything "works" — until the real table crosses 500 (or 2000) rows and records start vanishing from galleries with no error at all.

In practice

Treat the blue underline as a build-breaker. Restructure the query with delegable operators for your connector, or push the logic into a Dataverse view. Test against a table seeded beyond the row limit.

When it doesn't apply

Genuinely small, capped datasets (a lookup of 30 categories) can carry a documented warning.

Sources

• Microsoft Learn — Understand delegation — Delegable operators per connector