In the latest snapshot we have seen a fix implemented for update suppression, the fix seems to have reversed the order in which powered and activator rails power and un-power.

To Replicate:

• Place down a line of 9 powered rails.
• Place down observers which react to the blckstate of each rail.
• Place a solid block at the back of each observer.
• Place down a command block with the commands "say #" where # is a number from 1 to 9 for each rail segment.
• Place a redstone block at the rail corresponding to the 9th segment such that it powers the rails.

Observe:

In all version prior to the snapshot, the commands read in the order 1 to 9 in the chat with 1 being printed into the chat first and 9 being printed last

In snapshot 22w11a, the commands read in the reverse order 9 to 1 with 9 being printed first in the chat and 1 being printed last.

The significance of this is that players are accustomed to the status quo being the normal behaviour of rails, and because rails form such a crucial element of basically all wiring in technical contraptions due to being significantly more lag efficient than redstone dust. Basically every technical contraption built up to this point is going to be broken in some way due to some rail based wiring somewhere that schedules events in the wrong order.