Sometimes, reaction bars (the divs with the good sh*t and reaction buttons) from the post under are "above" the reactions box. I've only noticed it when the post under is mine, but it could be for anyone's.

If I give the reaction bar a negative z-index, or remove it altogether, I can reach that last row of reactions.

I hope you can understand how I worded this

yea ive been unable to use certain reactions before because they overlap w/ the next posts's buttons