I have been reusing my yeast for some time now. But I have never had a jar do this. It is WLP028. Nothing special as I have made this before. Only change was Magnum hopes in place of Centennial. Fermentation stopped at 1.016. Removed the beer and collected the cake off the bottom. Shook it hard and refrigerated to what you see here.
What half do I save?
It looks like you have a lot of CO2 trapped in some of the cake. I’d expect it all to drop out in a day or so, especially if you let it sit out.
Is that cap loose? I would loosen it.
I regularly re-use my yeast.
Occaisionally, I have the same thing.
It doesn’t seem to be an issue, I just give it a good shaking before I re-pitch.
As noted, the lid needs to be kept loose to allow any CO2 to escape.
Oh weird, I just had this happen to me for the first time the other day. Not quite to that extent, but I had a layer of yeast on top of the clear beer, maybe half an inch; that had never occurred before. I gave it a shake and it all settled out as normal.