I had heard they had rewritten it in go and got a lot more performant, not sure what else they have done. I don't care much about the politics as long as it's still open source (is it?).

That said, I'm a happy nextcloud user and I don't see a reason to switch (after moving both data and db onto SSDs it's much faster, so maybe php wasn't the bottleneck).

That's interesting that they refactored it. Maybe there have been some improvements made over the last seven years.