The regeneration effect from beacons is slower than regular regeneration because it is being reapplied every 4 seconds

the video attached shows a demonstration of:

normal regeneration 1 regenerating slightly faster than starvation damage, which overcomes starvation

a redstone clock with a timer of 4 seconds connected to a command block applying regeneration 1 regenerating at the same speed as starvation damage which cannot overcome starvation

a beacon which also applies regeneration 1 every 4 seconds also regenerating at the same speed as starvation damage which cannot overcome starvation

Considering the cost of a level 4 beacon, I feel this bug should have been fixed to let beacons give the full regeneration 1 speed a long time ago