If the mod is supposed to provide info boxes containing descriptions of different potion effects it is not currently doing anything. Clicking on potion effects anywhere in the gui does nothing.

Minecraft version 1.21.1
Neoforge 21.1.119
JEI 19.21.0.247
JEED 1.21-2.2.15

No other mods installed

and R doesnt work either?

Reverting to JEED version 1.21-2.2.14 fixed the issue.

R/U work on other items in JEI, but not on potion effects.

Does clicking on items do anything?

JEI functions as expected. Left/right clicking on items shows their uses and recipes.

fixed