Seems that an instances gets stuck somehow after or during startup and where Find calls throw this exception:

System.NullReferenceException: Object reference not set to an instance of an object.
   at EPiServer.Find.Api.Command.GetResponse[TResult](IJsonRequest request)
   at EPiServer.Find.Api.SearchCommand`1.Execute()
   at EPiServer.Find.Client.Search[TResult](SearchRequestBody requestBody, Action`1 commandAction)
   at EPiServer.Find.SearchExtensions.GetProjectedResult[TResult](ISearch`1 search, SearchContext context)
   at EPiServer.Find.SearchExtensions.GetResult[TResult](ISearch`1 search)
   at EPiServer.Find.Cms.SearchRequestExtensions.GetContentResult[TContentData](ITypeSearch`1 search, Int32 cacheForSeconds, Boolean cacheForEditorsAndAdmins)

DXP Log Stream also have these that looks related:

Serialization and deserialization of 'System.Reflection.MethodBase' instances is not supported. Path: $.TargetSite. Serialization and deserialization of 'System.Reflection.MethodBase' instances is not supported.   
Exception type    
System.NotSupportedException   

Most instances seem to work fine and restarting seems to usually bypass the issue.

We have a support case running but anyone seen this too?