This has been the case since around 1.19.10, where if I try to enter something into a command block using /Execute, I get a syntax error. What happens is once I finish the command, e.g. "/execute @p[x=~,y=~,z=~,r=2,c=1]~ ~ ~ tag @s add ___" this syntax error goes into previous output. What SHOULD happen is the player triggering the command block gets a tag, for example, "player".