For my understanding (but maybe I am completely wrong) a vendor update will update the vendor software pre-installed in the stock rom MIUI (for me: bloatware). If you are on a different = custom rom (like LOS or CrDroid) you don't need such a vendor update - at least I never did so and missed nothing. If you update the custom rom, all needed files will be updated.Thanks, so, to summarize about the firmware: we can try different ones and revert easily if there is a problem.
Do you have experience with flashing a vendor update? https://xiaomifirmwareupdater.com/vendor/ginkgo/
I cannot find other sources of information about this.
see here: https://forum.xda-developers.com/t/how-i-update-vendor-firmware-on-lineageos-16.4006271/
... not in order to do so but to see the comment to this post