ATOM service return NullPointerException error

We are getting a NullPointerException error related to the ATOM download service metadata. Until December 2023, if these errors occurred, they were very rare, and in the last 2 months they became regular for most metadata of the ATOM service. For example, checking the link manually (https://www.inspire-geoportal.lt/geonetwork/srv/eng/atom.predefined.service?uuid=9dae39cb-aad2-478c-a0cb-dd40c3a9b32d), we get a positive response for several times, until the time a NullPointerException error occurs. Maybe you have any ideas, what reasons can lead to this? Geonetwork version is 3.10.3.0

Start by reproducing the ATOM service request at the linked URL on GeoNetwork 3.10.3.0 and collect the NullPointerException stack trace from the service logs. Compare successful and failing responses and trace the metadata handling path; done means identifying the cause and documenting a reliable fix or reproduction.

Written by the indexing model from the issue text.