As for the original question (before we all got side tracked!) my money is on the "improved" springs. Every cottage gun parts vendor is smarter than the engineers who designed (any) pistol. Manufacturers are rightly obsessed with reliability as am I with carry pistols. Restore the pistol to stock condition before making any judgements as the "improved" springs may just be worn out since you seem to shoot enough ammo to justify reloads.

For curiosity I just now measured the trigger weight of my new (Sep 2023) standard P365 at 3# 15oz (average of 10) so I'm not sure where guys are getting 7# triggers. SIG OEM flat trigger probably helps with leverage. I don't trust single action pistols without manual safeties especially not with 4 pound triggers. Guys playing with spring kits should keep this in mind for carry pistols.

-- Chuck