DarkNecridovement speed penalty so that it actually works properly and remove random fall damage, I believe in you Valve!Can you explain it a bit?
Backwards movement speed penalty
Supposed to be -10% when walking backwards, hasn't worked properly for 11 years now. Moving diagonally increases your movement speed which is normally prevented by each class having a ground movement speed cap, except moving backwards doesn't temporarily decrease your movement speed cap to match the -10% penalty so if you hit any strafe key & S at the same time you bypass the penalty entirely and move at full speed (you can see this with cl_showpos 1 in console).
This is something people involuntarily do even if they're not aware of this because holding only S is awful.
The -10% penalty exists to disadvantage retreating and to make players choose between worsening their retreat but being able to fight back or moving at full speed but turning away from their attackers.
However, since everyone bypasses it very easily there's no disadvantage to retreating & fighting back, in fact turning away from your attackers is just worse if you have the map memorized since you're just moving at the same speed as walking backwards but not able to fight back/surf rockets as easily.
Fixing this mechanic would actually help pushes a bit, you'd be able to close the distance on people fighting back at you and at lasts retreating into spawn when attackers are close would force you to not fight back to maximize your ability to tap the resupply.
Random fall damage
Not much to explain, random fall damage is always enabled because tf_damage_disablespread 1 only applies to weapons/buildings and not world damage which is what fall damage is. Every time you take fall damage it's RNG how much you'll take and it's really the biggest source of RNG left in competitive play. While the damage spread is not immense or anything, it is more than enough to make a Medic surf that leaves you at low HP pure luck if you live when you hit the ground or not.