"Save" button is missing from the case form in native UI post Orlando upgrade, only the 'Submit' button is available.
This is the expected behavior.
In London, Madrid, and Orlando - "SAVE" button((Sys_Id: c2403034c33231005f76b2c712d3ae86)) is not visible for the New Cases.
Save Button Condition: !(current.isNewRecord() && !current.canCreate()) && current.canWrite().