A bug where water blocks in Minecraft do not flow

I built a redstone device in my game Minecraft and found a bug about water, the bug overview is that water does not flow, I can confirm that it is not my problem.
Because the water on both sides can flow, I asked my 8 friends on a third-party platform, they couldn't solve it, and finally I decided it was a bug, version 1.21.8 launcher official launcher