Beacons have a weird gap at each corner where every effect disappears. Smart players know that beacons remove effects by each step you walk away after 50 blocks. The corners fully remove every effect until you walk back into the effected area of the beacons range

Steps:

1. Create a New World [Optional if you have an existing world with a beacon]
2. enter world in creative
3. Use any blocks that can at least make a maxed out beacon [I recommend a sextuple beacon]
4. make a perimeter around the whole beacon
5. go to the corner edges [every effect should be removed] then walk back into the of range/side of the beacon [Every effect should return if they all pop up]
6. go back into the gap and wait for the effects to start flickering, then head on the other part of the perimeter [if you're confused, same area just the other side of the perimeter] the effects should reappear again

The evidence in the video is quite confusing but i assure you the steps i hope will help