I have also seen this since the last couple "updates" to AGOL.
Seems it happens a lot more on Chrome than Edge, and is pretty random. Tried to ty it to AGOL server not functioning properly, but according to the ArcGIS Online Health Dashboard, it always reports it as Green, but, that seems to be the case even when some of the servers aren't responding at all. So, still could be, but if so, why do some layers in the hosted FS draw, and others say failed to load?
I even pushed new datasets from Pro and add them with the same results. Random as to which layers within the feature service draw vs. don't. However, for some reason, they all load into Field Maps app just fine.
Of course, currently they seem to be working fine, so is random enough, no way for me to reproduce for tech support.
I am working in WA state plane, but all my data, basemaps, etc. are in the same SR, and defined.
R_