Started to use PE2021.7.2 and see these warnings with an exception stack periodically

2023-02-15T15:18:33.932-05:00 WARN  [qtp1315451208-212001] [o.e.j.s.HttpChannel] /puppet/v3/environment_classes
clojure.lang.ExceptionInfo: Output of manifest-info-from-jruby->manifest-info-for-json does not match schema: 

	   {:classes [{:params [nil {:type (not (instance? java.lang.String nil))} nil]}]}  


	at puppetlabs.services.master.master_core$fn__29665$manifest_info_from_jruby__GT_manifest_info_for_json__29670.invoke(master_core.clj:269)
	at clojure.core$map$fn__5935.invoke(core.clj:2770)

What could be the reason ?