@CircusPeanut I had the issue before updating to v11.1 so I don't think it is caused by v11.1
...
ERROR: AcceptToMemoryPool : nonstandard transaction: scriptpubkey
...
ERROR: AcceptToMemoryPool : inputs already spent
...
ERROR: AcceptToMemoryPool : free transaction rejected by rate limiter
All of these error messages may be wrong. I was getting multiple different issues on my test cases.
I think scriptpubkey was for unnecessary 0x00 padding (a different malleability issue).
I'm pretty sure the ERROR for Low S violation in 0.11.1 is:
ERROR: .... Non-canonical signature: S value is unnecessarily high