This seems to be a partial regression of MCPE-12443, but I've created a new ticket as I think the base issue is different.

Angered pigmen do not run fast enough; the player is able to outpace them by walking.

According to the wiki:

When aggravated, their speed will significantly increase to faster than the player's walking speed.

I think changing the speed multiplier from 1 to 1.5 in the vanilla behaviour file for this mob would fix this:

"minecraft:behavior.melee_attack": {
        "priority": 3,
        "speed_multiplier": 1.5,
        "track_target": false
      },