Создай скорборд: scoreboard objectives add tnt_run dummy
Во время игры активируй следующий механизм:
execute as @a[nbt={OnGround:1b}] at @s align xyz positioned ~.5 ~ ~.5 unless entity @e[type=minecraft:armor_stand,tag=tnt_run,distance=...5] run summon minecraft:armor_stand ~ ~ ~ {Tags:["tnt_run"],Marker:1b,Invisible:1b,Silent:1b}
execute as @e[type=minecraft:armor_stand,tag=tnt_run] unless score @s tnt_run matches 0.. run scoreboard players set @s tnt_run 5 (через 5 тиков удалиться блок)
scoreboard players remove @e[type=minecraft:armor_stand,tag=tnt_run] tnt_run 1
execute at @e[type=minecraft:armor_stand,tag=tnt_run,scores={tnt_run=0}] run setblock ~ ~-1 ~ minecraft:air
kill @e[type=minecraft:armor_stand,tag=tnt_run,scores={tnt_run=0}]