This is the list of available potion names as of 1.16.5. If you are using an older
server version, some of these names won't work as the potion you may be using
may not exist for your older version. 

AWKWARD  
FIRE_RESISTANCE  
INSTANT_DAMAGE   
INSTANT_HEAL     
INVISIBILITY     
JUMP     
LUCK     
MUNDANE  
NIGHT_VISION     
POISON   
REGEN    
SLOW_FALLING     
SLOWNESS     
SPEED    
STRENGTH     
THICK    
TURTLE_MASTER    
UNCRAFTABLE  
WATER    
WATER_BREATHING  
WEAKNESS