Tick Bitmap Index section

[wailokmonad]

...
initialized = masked != 0;
next = initialized
    ? (compressed - int24(uint24(bitPos - BitMath.mostSignificantBit(masked)))) * tickSpacing
    : (compressed - int24(uint24(bitPos))) * tickSpacing;
...

When initialized = false, you claim it should return the RIGHTMOST in the word, which is also the comment on uniswap-v3 source code. But the line (compressed - int24(uint24(bitPos))) actually return the LEFTMOST of the word. Why is this happening?