It still works fine for me but I still cannot reproduce that parsers are added by other threads.
To test the fix, update the bundle on the Karaf console using one of these commands and then restart openHAB.
OH 4.0.x
bundle:update org.openhab.core.model.core https://github.com/wborn/openhab-core/releases/download/folder-observer-20231020/org.openhab.core.model.core-4.0.4-SNAPSHOT.jar
Recent OH 4.1.0-SNAPSHOTs or OH 4.1.0.M2
bundle:update org.openhab.core.model.core https://github.com/wborn/openhab-core/releases/download/folder-observer-20231020/org.openhab.core.model.core-4.1.0-SNAPSHOT.jar