In SERVER-80363, we implemented new logic to address write concerns that lacked the 'w' field by filling it with information from the default write concern. However, in the process, we overlooked instances where the locally constructed batchRequest write concern was still being used (ex), leading to inconsistencies.

This ticket aims to rectify this issue by ensuring that batch requests omit the write concern parsing if the 'w' field is missing, aligning with the changes made in SERVER-80363. We anticipate that any locally constructed batchRequest will have the correct 'w' field for the write concern. Furthermore, we will undo any overwriting of write concerns in Cluster::Write, where the caller sets the write concern.

Additionally, there's another ticket (SERVER-83193) focused on entirely removing the write concern from batch requests, which will address this matter comprehensively.