It definitely appears to be counterspell. It bears the description for counterspell on the reactions tab (see link below).
[img]
https://www.nexusmods.com/baldursgate3/images/16447[/img]
Looks like others have experienced this bug with vengeance paladins. Looking at the list of mods presented in the discussion below, the only one I have installed is stock scrolls, a mod which I have never used before. I will see if I can disable the mod (or start a new run without the mod) to see if the problem goes away.
https://www.reddit.com/r/BaldursGate3/comments/18ofb2h/why_tf_do_i_have_a_free_counterspell/
