hot_standby_feedback via intermediate replica

Hi all,

I’m getting:
- - -
pg_dump: error: Error message from server: ERROR:  canceling statement due to conflict with recovery
ClientBeforeJob: DETAIL:  User was holding a relation lock for too long
- - -
I have a 3-level streaming replication setup:
    primary -> standby1 -> standby2
standby2 is for backup only and shows above error.
Both standbys have
    hot_standby_feedback = on
Nvertheless the error happens.
Why?
How can I fix it?

All are running 13.7

Any help appreciated,
Axel
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PGP-Key: CDE74120  ☀  computing @ chaos claudius