Your assumptions are very outdated. App Store review times are typically < 24 hours and have been for the last couple of years. And KMP makes cross-platform a real thing now, rather than hacking a web view into a native shell, which was always the worst possible user experience.
I'm afraid you are the one out of date here. App Store Review times have ballooned in the last few months. Marco Arment talked about this publically (on the ATP podcast) about how his app was stuck in review for over 2 weeks IIRC and I've seen 2 days as the minimum review time in the last few months with some taking a week or more.
Yes, for a while they were doing very well and I even once had an app reviewed in <1hr but the average has been creeping up. LLM/Vibe coding is what is often blamed for this increase though at the end of the day it's Apple's problem/fault for not staffing the review department better.
Doesn't KMP assume your team is comfortable working in Kotlin?
Apple has started automating them a while ago so a lot of them are indeed <24 hrs. I wouldn't say they are wrong though.
Just this week I've had an app stay for 9 days in review and another one for 8 hours. Same dev account, same niche.