ISR 4k - BFD QoS

So I'm reading this article from Cisco that says this

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BFD packets are not matched in the QoS policy for self-generated packets.

1- https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bfd/configuration/15-mt/irb-15-mt-book/irb-bi-fwd-det.html

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When I try it on an ISR 4-k (output qos policy-map) I never see any packets matching BFD (outbound). So how do I guarantee that during times of congestion these packets will go out first? I know there's pakpriority but does that feature understand that i have shaping my WAN link?

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