Those BKRK are related system processes and back end connections and do not count upon the limit of connections associated with every service tier. They can safely be ignored. BKRK processes are related to service broker on on-premises SQL Server instances and Azure SQL Database may be using it as part of the service it provides.
With Azure SQL Database you will always see many connections and processes related to the automated features the PaaS provides to the customer. Learn more about back end connections here.
Instead of focus on system processes, please try to know if blocking is the culprit.
from sys.dm_exec_requests r
join sys.dm_exec_sessions s
Consider also deadlocks may be a possibility, and you can find them using below query.
where event_type <> 'connection_successful'
and start_time >= CAST(FLOOR(CAST(getdate() AS float)) AS DATETIME)
order by start_time desc -- event type = deadlock