The trust flag at the projetc level is only used to read vector layer extent from xml, not from provider.
This flag was not available at the vector layer and data provider level.
We propose a new QgsMapLayer reading flag to propagate the trust layer metadata prohect's read flag an d a new provider options to trust datasource config.
Trusting the datasource config means that the provider can use estimated metadata, the primary key is unique and the detectable geometry type and srid are the same as the requested.
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