Patching after upgrade (windows 11gr2 -> 12cR2) I have a following scenario where I had a patched oracle 11gR2 DB (applied Windows Bundle and OJVM patches) and then it was upgrade to Oracle 12cR2. 12cR2 was a clean installation (no patches applied, just a download).

In the case above then do I need to apply “same” patches again to my upgrade 12cR2 DB?

I am talking about patchset bundles. I did apply to 11gR2 a Windows Bundle patches and OJVM PSU.

So just to be clear: To have a "same" level of patching then I need to install corresponding 12cR2 patch? For example I had a 2018 jul patch installed to 11c and now I would need to install "again" 2018 jul, but for 12c (I would install again Windows BP and OJVM PSU)? I understand that 11c patch might have fixed a bug, which is in 11c and 12c, but it does not fix a bug in 12c. As I was saying then I need to be sure..

For the future then I should apply patches before I would do the upgrade?
That would depend on what the "same" patches are.  At the very least, you'd need the patch specifically for the new version of the database.  But it could be that the the 11g patch fixed something in 11g that was inherently fixed in 12c.  You just have to look at each patch on a case-by-case basis.  Also, are you talking about individual patches or patchset bundles?  If the latter, simply apply the latest for your version of the database.