There is no doubt that the design & implementation of MSFS 2020 Multiplayer has numerous flaw
but
It is often made worse by inexperienced Livery developer, who create liveries with multiple type of flaws, many of which present in Multiplayer.
Initially there was not much official documentation as to how to “correctly” create a new livery, and those trying to do so, figured it out for themselves, by trail and error, often by doing things that caused issues.
This has improved, but there are still many older liveries out that that break fundamental rules, and cause issues - especially when the sim gets a SU,
Add to that that many Developers do not seem to pay much attention to Multiplayer, and it’s design requirement, when they put together their planes, and it is not until their planes are launched on a Multiplayer community, that issues become apparent.
The good news is that it is Possible now to produce both Plnaes and additional a liveries, that works in MP, and are mostly SU tolerant.
But basic Model matching in MP still remains an issue, waiting to be fixed by Asobo.
Most, if not all the reasons for Model matching failure have now been identified by the community (in particular by Wombii) but it remains unclear to the community, how aware Asobo are aware of the problem, the solution, and if they now consider it a high enough priority to address.
A few Twitch streamed MP sessions, with some of the Technical Asobo Devs (not Community Managers), taking part, might help move progress forward, as they experience what we all see in a worldwide user, Internet MP session.