slow query on CDB_FREE_SPACE

I have the next issue:
-> query on CDB_FREE_SPACE is slow , issue being located in a particular
PDB
-> querying DBA_FREE_SPACE in problematic PDB I can see issue is caused by
execution plan full scanning X$KTFBUE
-> I gathered stats on X$KTFBUE and issue was still there
-> I observed that setting optimizer_adaptive_plans to false will do the
trick
-> went back in container , set optimizer_adaptive_plans to false at
session level and worked, so I thought great, I`ll create a sql patch with hint opt_param('optimizer_adaptive_plans' 'false') but when hint is applied in the query from CDB$ROOT is not propagated into PDBs (is working only with alter session). The hint is working if I switch to PDB and run the query with the hint there.

Any ideas on how to solve this problem?

Thank you.

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