I'm using the first person mod (Minecraft 1.21.8 // fabric-installer-1.1.0).
When I lay down to crawl, the camera shoots down before my character's body is in position.
And when I stand back up, the camera shoots back up before my character's body has stood up and I see for a moment the headless body.
It's a bit emersion breaking.

I want to ask for a checkbox option or a slider please,
to adjust the speed with which the camera gets into position, so that my character's body doesn't get left behind.

Laying down:

Standing up:

I would also like to ask for an option to reduce the camera movability while climbing a ladder, like when using boats, so that you can't look behind like an owl, or at your own neck.

The camera position drops to a weird height, while holding shift on a ladder.

Using a bow on a ladder looks weird. ... Not sure what I could suggest, besides a no (cross)bows allowed on ladders check box.