The Bug.

When a chunk containing tile ticks gets loaded, all the tile ticks will run instantly in the first tick

This causes huge problems when reloading chunks with precise (or even imprecise) redstone circuits

ExtendedTileTickDetector.mp4: This circuit detects when one of the observer's tile tick delay gets changed
Overflowing the tile tick limit will cause all other active tile ticks that were going to be processed in that tick, to be moved to the next tick
Reloading a chunk will instantly run all active tile ticks

The bug was added in 1.14.2
1.14.0 and below is unaffected
(The detector doesn't work at all in 1.14.1 because of another bug)