I looked at their hp at damage upgrade 7 and it was 837. I got another damage upgrade and now they have 1128. At upgrade 7 your turrets have +120% damage and that stacks with +120% ammo damage resulting in 2.2^2=4.84 damage multiplier. Divide 837 by 4.84 and you get about 173. With upgrade 8, turrets deal 2.4^2=5.76x damage. Divide 1128 by 5.76 and you get about 196. So the trashsteroid effective hp went UP, not down.

It looks like whatever scaling algorithm you have, it's adding too much hp.

Hey McFugal. Thank you for the report. Based on my own hand-calculations, trashsteroid total HP should only increase by 5.1% between those two levels. However, I need more information, since there are many things that affect trashsteroid scaling:

1) Is this Rubia’s normal difficulty (mod setting)?
2) What is your weapon shoot speed upgrade level? Please show the total multiplier bonus.
3) Do you have Krastorio 2 installed? If so, is it set to realistic weapons mode (its default mod setting)?
4) Do you have any mods that affect the turret dmg multiplier OR physical ammo damage bonuses? Please confirm the total dmg bonus for both of these in the Bonuses menu (top right corner, up arrow icon shows the actual current ingame bonus).
5) When reporting these shields, are you certain that this is trashsteroid max HP + current shield, when the trashsteroid spawns?
6) Could you run this console command on the save to confirm the total HP of the trashsteroids that the game is supposed to spawn? Type this into the game chat (you may need to do this twice to enable console commands. Just reload after if you don’t want to mess with achievments):

/c __rubia__ rubia.testing.show_difficulty_scaling()

This shows the shielding that Rubia believes it should be currently applying.

Sorry to request so much additional information from you, but I will need this to be able to know exactly what is going on. Basically, this is either: 1) miscalculation/misreporting, 2) Rubia not updating the HP frequently enough, 3) other mods messing with calculation, 4) dmg formula error, 5) dmg bonus read error. The info I requested will help me get to the bottom of this.

Right now, the numbers you gave me make sense for (going by the numbering above): 1) normal difficulty, 2) shoot speed lvl 5, 3) no K2SO, 4) no other mods, 5) you reported shield (not shield + HP). With this, trashsteroid shields should be 837 with shoot speed lvl 5 + phys dmg lvl 7 (total gun DPS multiplier = 2.2^2 * 2.1= 10.16x, with the 2.1 from +110% shoot speed bonus), followed by trashsteroid shields of 1128 for shoot speed lvl 6 + phys dmg lvl 7 (total DPS multiplier = 2.4^2 * 2.5 = 14.4x). This difference would be 14.4 / 10.16 = 1.417x to your total gun DPS.

1, I'm on normal difficulty.
2, Shooting speed is 6, resulting in +150%. Why would that affect hp? The planet tutorial only mentions damage upgrades, and for that matter it shouldn't affect it imo-- the most impactful thing is ammo efficiency. Shooting speed improvements just mean you need less turrets, and that isn't really a major factor... plus by the time you can get to Rubia you will have almost all of the shooting speed improvements already.
3, no K2.
4, doesn't look like anything else is affecting turret damage. Just +140% for turret and ammo.
5, I'm mousing over the trashteroid and it displays as 1128/1200.
6, it says "Current damage multiplier = 14.4. Current shielding amount = 1128.8236992559

Anyway, I'm guessing it's like this because I researched another shooting speed upgrade before that damage upgrade. Again, the tutorial text only says it scales with damage upgrades, so this was unexpected.

The Trashsteroid Mechanics Tips And Tricks entry specifies weapon shooting speed is included in the calculation. Shooting speed matters because they scale off your DPS, not just raw damage per hit.

I'm closing this out as resolved, since everything is working as intended.