If I'm eating an item and have blocks in my off-hand, holding right click will eat until my hunger bar is full then immediately place a block. This is kinda annoying and I would maybe expect to need to release then re-press right click to use the off-hand.

I've also done this with an axe in the off-hand, accidentally stripping a log. Also with a spyglass in the off-hand, abruptly zooming in when done eating (which is visually annoying but not too bad).

I think with some things this behavior could be convenient sense, like with a hoe in the main-hand and seeds in the off-hand, you can hold right click to continuously till the land then place seeds. But with eating (and maybe other things?) I think it's a little troublesome.