extra nonce?

[superNoobMiner]

I am getting messages like this with bitcoind.  I understand that this is an indication of a valid proof of work.  The part I do not get is the "26 of the last 100 blocks have unexpected version"

2018-12-02T11:59:36Z UpdateTip: new best=00000000000000000025f33f934ce1f4a25899468b945107d0e8761bcab05e17 height=552263 version=0x20000000 log2_work=90.085067 tx=361390465 date='2018-12-02T11:59:18Z' progress=1.000000 cache=3.8MiB(28145txo) warning='26 of last 100 blocks have unexpected version'


Is this common?  Is this an indication of "extra nonce"?  Is there an online reference to aceptable strategies of extra nonce?

As my name indicates, I am new.  Even basic information would be appreciated.

[omegalulz]

This is probably due to ASICboost version rolling.


https://asicboost.dance/