UnsatisfiedMind

This can also be reproduced in 1.21.5 single player world by entering the nether.

While in the nether, the bamboo in the spawn chunk farm continues to grow, but the pistons will not trigger to trim them. Farms outside the spawn chunks seem unaffected, as the bamboo does not grow.

In a 1.21.4 world, the bamboo does not appear to grow while the user is in the nether, even when the bamboo is in the spawn chunks.

I’ve continued to try to debug this.

I can reproduce it in a separate 1.21.5 world in the spawn chunks, but I cannot reproduce it in a 1.21.4 world.

In a 1.21.5 world, a bamboo farm in the spawn chunks eventually overgrows due to the pistons not firing, but a bamboo farm outside the spawn chunks does not exhibit the behavior.

In a 1.21.4 world, the world seems to pause once the player is AFK on the “You Died!” screen, there is no growth in the farm.

Changing spawnChunkRadius didn’t affect my issue.

The quickest way for me to get the bamboo to be overgrown is to die near the bamboo farm and leave myself on the “You Died!” screen. If I leave myself there for several minutes and respawn, when I return to the farm at least some of the bamboo will be overgrown.

I am able to reproduce the piston not firing when chopping the bamboo manually, as in the attached video.

The recording has no audio, but I setup dispensers with rockets to test whether it’s the observer or piston that’s not firing, and based on my tests, it appears that the observer is firing, as the rockets dispense when I chop down the bamboo, even if the piston does not extend.

I’m experiencing something similar on a solo world.
I have a small basic bamboo farm (12 observers, 12 pistons) in a spawn chunk.

Since upgrading to 1.21.5, each observer/piston pair in the farm will eventually stop working, which I take it mean that the observer is sometimes failing to detect the leafy growth of the bamboo.

Not every pair stops working at the same time, but eventually all do stop.

If I manually chop the tops of the bamboo, the observer/piston pairs will start working again for some period of time, but again, all will eventually stall.

I have a sugarcane farm in the spawn chunks as well and it has never experienced this issue.

This was not a problem on any previous version of 1.21.

This can be closed. I still had some old 1.21.4 Vanilla Tweaks datapacks installed. Once I removed those, the frog behavior returned to normal.