i noticed that worms tend to get way higher dmg boost than spitters for the same tech tier.

at tier 153:
big worm dmg:
splash: 57.6/s + 15k/s
spit dmg: 48 + 13k

big spitter:
splash: 130/s + 1.98k/s
spit dmg: 36 + 551

all settings are default.

That's because there are two modifiers applying to them - just like for player's turrets.

+ammo_damage (in this case, "Biological" category) affects the acid spit attack, both for Spitters and Worms
+turret_damage for Worms (worms are a turret internally)

And just like player equivalents, these stack multiplicatively, so Worms get way more dangerous with upgrades.

damn, that means that even on low settings (0.01 dmg per tier) legendary behemoth worms can practically 1 hit ko everything long before even getting anywhere close to the default max tier (10k).