All those updates for insider (especially Experimental channesl) are for testing next Windows versio and those are usually released weekly, thats part of being insider.
Is this device which you need for daily works?
It's not recommend to use insider preview devices that are needed for daily work.
That SID S-1-15-3 is Windows own internal Capability SID which you don't have to worry.
Capability SIDs serve as unique and immutable identifiers for capabilities. A capability represents an unforgeable token of authority that grants Universal Windows Applications access to resources (for example, documents, cameras, and locations). An app that has a capability is granted access to the resource that the capability is associated with. An app that doesn't have a capability is denied access to the resource.