Samsung has always surpassed Apple in “smartphone technology”.
Samsung is clearly the best manufacturer of small screen OLEDs, hence why Apple needs to rely on them, and can’t use LG as redundancy.
Samsung is clearly the best manufacturer of solid state storage and RAM, followed by SanDisk / Toshiba, recently merged with Western Digital, so they can keep the 2nd place. That’s why Apple uses almost exclusively Samsung for their Macs (it’s been a while since I saw Toshiba on them) but still uses mostly SanDisk and Micron for the iPhones. But Apple likes redundancy, so there may be some iPhones with Samsung storage and Macs with SanDisk.
Samsung is one of the three factories that can manufacturer high density CPUs and SoC, next to Intel and TSMC. AMD, for example, no longer manufacture their own CPUs, delegating to TSMC, like Apple does. Once again, Apple like redundancy, so at least the 6S Ax SoC could be made either by TSMC or by Samsung.
So clearly Samsung Electronics, the “Silicon” division, is one of the best in the world.
That’s why smartphones are assembled mediocrely, with the Samsung own components being the best, as a showcase of their technology, but the components not from them, including the software, being not more than “good enough”.

Apple knows how to make a full end to end product, not even counting the ecosystem around. Samsung doesn’t. I know. I’ve done two devices with them and it was painful.
Not saying their products are not great. But they are not designed for the 110% like Apple does… did? No. They aim for the “good enough”. People get what they ask for, and Samsung does exactly as much as people need.
Which begs the relevant question of what is best, as sometimes it’s irrelevant if something is overall best, when something else is “best for me” because it’s cheaper and it’s more than I need.