[Xiaomi Redmi Note 5 Pro Questions & Answers] Alister.:
I've asked this type of thing before, and had a few developers try to answer it it's messy. The idea is Samsung, LG, Xiaomi every manufacturer has there own default rom.

They call theirs stock, that's their version of stock, it's customised only AOSP is truly stock, but the manufacturers versions of their "own" stock roms include a binary also referred to as binary, blobs, it's pretty much a closed source driver each manufacturer makes so their default camera looks amazing.

A general idea is replacing stock rom from any manufacturer with any that isn't based of their "own" stock rom isn't going to include their camera driver as it's closed source, so developers can't use it, they can get the cameras working but they don't look great compared to stock with binary. Lots of people avoid custom roms lineage os aosp ect for this reason video calls, all apps using the camera look terrible.

Two exceptions google open sources there camera drivers and oneplus might be some rare others, in these cases camera quality is expected to be the same while using lineage os or aosp.

I'm not 100% sure if all apps use camera1 and camera2 api if you try look for whatsapp or google duo i couldn't confirm it for them, snapchat uses camera1 api instagram uses camera2 api, but maybe some apps don't benefit from camera2 api at all i'm unsure.

I also tried asking if google camera ports, look better on stock roms that have the binary driver from companies, compared to lineage os ect that don't have it, but that's unclear as even tho i'm 100% sure the binary from manufacturers benefit there own made camera apps, i'm not 100% if the binary benefits all third party apps, but i guess it does, as that's likely the reason all apps look worse moving away from stock roms.

Google camera ports may look great on roms without, the binary as they simply make use of camera2 api which doesn't really require anything from the closed source driver, which would explain why everyone raves about google camera ports on lineage os ect been great, before camera 2 api never saw people been overly impressed about camera apps with missing binary drivers.

Are you on MIUI or something else? you did say the stock camera app not google camera looks good and everything else looks worse, if your still on MIUI then maybe they don't have a binary or simply one that only effects there own camera app, you mentioned the camera lens quality also it's mostly software driver optimisations per individual app ect influencing it's quality.

You asked how to make other apps use google cameras driver, well google camera is benefiting from camera2 api that isn't a driver at all, however it is a requirement similar aspect to a driver it's up to each app developer if there going to make there, application benefit from camera1 api or camera2 api or not at all, so you cant force apps to use it when the developer of that app never implemented camera2 api to begin with, you enable camera2 api for google camera because custom roms and lots of phones don't have it enabled at all. Some phones sold from stores have camera2 api enabled out of the box.

I do actually wish there was a way to fix this, as i've thought about this myself, i did ask a question here about the same type of thing you can read it if you like.

https://android.stackexchange.com/questions/200073/stock-os-vs-custom-proprietary-camera

also this the different levels of camera2 api supported depending on your phone

https://www.androidexplained.com/camera2-api-support/

the only other idea, i have is if the rom you use lets you choose the stock camera app to use and you change that to google camera and whatever, but i'm sure that's wishful thinking as when you do a video call an app will likely default to it's own camera even if you do that, but couldn't hurt to try it i guess!