I do following other than just testing.
– Engage with BA/PO in product backlog refinement
-Analyse gaps in the existing application and work with PO to write stories
-Application Code walkthrough with developers and attend their technical meetings, to prepare what changes are coming and impact of those changes.
-Investigate the failures or bugs at application log level to isolate the issue to possible smallest unit of module
-Help developers giving the right context of application to fix the issues
and many more….