I am a long time 1Password user, have started with 1Password 6 and took every release afterwards. As you might know, 1Password 8 is not very popular compared to previous versions due to the fact that they changed from being a native Mac app with code base as well as look and feel to some kind of Electron / Chromium based “native” app which feels more like a scaled-up iPad / mobile app. Not being the brightest reasons, but one of some smaller and bigger ones which brought me to the situation about thinking to switching to Bitwarden.
I have installed Bitwarden on my Mac and created a self-hosted vault with Vaultwarden on my server. Synchronisation works perfectly both on my Mac as well as on my iPhone and iPad devices. The only problem that came up, which is a show-stopper right now, is the absolutely bad performacne of Bitwarden compared to 1Password on all my devices.
After bringing in some googling, it seems that I am not the only one with this issue / problem:
There have occasionally been issues in the past with new releases of Bitwarden client apps or new browser releases, but these have been resolved (e.g., both of the GitHub issues you linked are closed). The first link you posted includes a number of trouble-shooting steps in the response to OP — have you tried them?