If you point a redstone signal with a strength of 1 into a block, that block will still power blocks touching it even though the signal should have run out.
MC-297827
Powering a block with a signal strength of 1 still powers adjacent blocks
Resolved
Invalid
0
Despite having a level of 15 the redstone wire is still able to “hard power” the block at the end of the line, this is not a bug.