Hello @the_french_SNO ,
Welcome to the forum!
You are likely correct, while disk under the load the database can be locked to add data, this usually suggest a slow disk.
However, your node is managed to lost some data accordingly this error:
So, I would suggest to stop the node and check and fix errors on the disk first. After that if the filewalker would still fail, then you may consider to enable the badger cache or migrate to hashstore.