out of pure curiosity I had a quick look in my 23c free attention.log.
beside some useful and reasonable entries there - generated due to my playing - I also found couple of these entries:
{
"WARNING" : "Container PDB$SEED has empty temporary tablespace TEMP. ",
"URGENCY" : "SOON",
"INFO" : "Additional Information Not Available",
"CAUSE" : "This condition occurred when a backup control file was restored. It may be necessary to add files to these tablespaces.",
"ACTION" : "If the temporary tablespaces are still needed, use ALTER TABLESPACE <tablespace_name> ADD TEMPFILE. Alternatively, if these temporary tablespaces are no longer needed, then they can be dropped.",
"CLASS" : "UNKNOWN / PDB / PDB ADMINISTRATOR / AL-16825",
"TIME" : "2023-04-04T15:20:31.564+00:00"
},
Maybe they should be removed from the attention.log unless there is a valid corrective action - but I couldn't find anything documented.