Mob doesnt spawn as how they should be

So i made a thread a few hours ago on how mob doesnt spawn in my world which is a small world because i set the worldborder to 30 i tried afk for 15-20 minutes to see if mob doesnt spawn or just spawn slowly. i tp @e @s and only got 2 creeper and 1 skeleton for a small world mob should spawn more frequently near each other as there is not much space they can spawn so i made a mob grinder and test will mob spawn there and not any single mob spawn there anyone have any idea why this is happening? im using 1.19.2 vanilla

I read that article and i still couldnt find why mob spawn is very low at my server