Environment:
We use three parts of the system: web, backend, and frontend.
To communicate with amplitude we use amplitude-js/8.18.5 SDK for the web part and the backend and frontend - we use HTTP V2 API.
Sometimes we observe an issue with custom user properties that we created on the web part. The web part is only the one part that creates and changes these custom user properties. Neither the backend nor frontend part do not set or changes these properties. Then, we expect that all these user properties should be applied to all other events from other parts of the system. The user_id user property is the same for all events from all the parts of the system. However, we have users who do not have our custom properties applied on the very first part of our system (web). After some amount of events for these users from other parts of the system these custom properties appear again for events. Almost all of the users who faced this issue were on September 19 when we saw a huge degradation across most of the amplitude services. However, there are several users that had this issue on September 18 and September 17.
So, the question from our side. Could we assume that these users ( September 18 and September 17) also belong to the degradation of amplitude services issue? Or it might be a persistent issue that just amplified with the degradation services issue?

Thank you for any help or advice.