My v25 server is only a test server, so the logs have not rolled over, but the log format should be the same as in restv2-diagnostics.log.  If you uncompress restv2-diagnostics.log.9.gz it should look similar.

Try this:
gunzip < restv2-diagnostics.log.9.gz > restv2-diagnostics.log.9.out

Some sample lines:

{"id":285,"t":"2025-08-25T16:14:30.783Z","hm":"DELETE","rp":"/api/v2/notificationGroups/2294751/subjects/557056","hs":204,"h":null,"d":54}
{"id":286,"t":"2025-08-25T16:14:30.799Z","tid":115,"u":"rharolde","sid":7059044,"c":"141.xxx.xxx.6","hm":"GET","rp":"/api/v2/users/25073845/favorites","qp":{"total":"true","limit":"20"},"h":{"Accept":"*/*"}}
{"id":288,"t":"2025-08-25T16:14:30.814Z","tid":179687,"u":"rharolde","sid":7059044,"c":"141.xxx.xxx.6","hm":"GET","rp":"/api/v2/notificationGroups/2294751/subjects","qp":{"total":"true","limit":"100","orderBy":"asc(name)","fields":"id,type,_links,name"},"h":{"Accept":"*/*"}}
{"id":289,"t":"2025-08-25T16:15:02.041Z","tid":179699,"u":"rharolde","sid":7059044,"c":"141.xxx.xxx.6","hm":"PATCH","rp":"/api/v2/sessions/current","qp":null,"h":{"Accept":"*/*","Content-Type":"application/merge-patch+json"}}
{"id":289,"t":"2025-08-25T16:15:02.089Z","hm":"PATCH","rp":"/api/v2/sessions/current","hs":200,"h":{"Content-Type":"application/hal+json"},"d":47}
{"id":290,"t":"2025-09-03T19:04:23.948Z","hm":"GET","rp":"/api/v2/sessions/current","hs":401,"h":{"Content-Type":"application/json"},"d":0}
 

Thanks! this made me think I had a zip tool issue. Using the native one in Windows is where I am having the issue. I have 7zip and that resolved it!