Redstone repeaters aren't saving their pending tick information. As a result, every time you exit and reload a world, every active repeater will be updated instantly instead of the delay it should have been.

This is crucial and can break any device that relies on redstone repeater delays.

Here's another way to think about it: If you send a 1 tick pulse into a repeater set to 4 ticks of delay, when should the repeater turn off? Exactly 4 ticks later! However, if you exit before the repeater turns off, the game assumes that 4 ticks have already passed, even if they didn't, and turns off the repeater instantly.

Every other edition of Minecraft stores this delay as a tile tick. Bedrock edition needs to as well. The code for Pending Ticks is already there.

Here's 2 video examples of this serious bug in action:

https://streamable.com/c3lm6
https://streamable.com/qiiml

In these videos we have a 1 tick pulse being sent into a 4 tick repeater. The line of 1 tick repeaters coming after it can indicate to us how long that repeater has been activated for. If we exit the game before that repeater was turned on, the signal is completely lost. If we exit the game while the repeater is on, the delay could become 1, 2, 3, or 4 ticks, when it should always be 4 no matter what.