there several things about that image that are not aligned with “center”
can you be more specific or annotate your image so others know what you are talking about?
The 4 activities Background Fun Studies Work are not vertically centered in the panel. You can see the words slightly clip into the bottom border of the panel ( This is when you choose Activity bar over Activity Pager or Activity Manager )
appears to be a regression here is how it looks on my plasma 5 panel height at 44
but below that height it begins to clip the lower case j and q
tho it does remain center justified vertically.
i would file a bug report at bug.kde.org and give them similar pics for different panel heights,
tho i don’t think much work is going on with the activities function of plasmashell so i would not expect much action on this.
I have opened a bug report, thanks for the help.