SQL Server 2017

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CREATE TABLE Features(
   featureId VARCHAR(50),
   title VARCHAR(50)
);

INSERT INTO Features VALUES ('feature1','Feature 1');
INSERT INTO Features VALUES ('feature2','Feature 2');
INSERT INTO Features VALUES ('feature3','Feature 2');

CREATE TABLE Tasks(
   featureId VARCHAR(50),
   workstreamId VARCHAR(50),
   title VARCHAR(50)
);

INSERT INTO Tasks VALUES ('feature1','workstream1','Task 1');
INSERT INTO Tasks VALUES ('feature2','workstream2','Task 2');
INSERT INTO Tasks VALUES ('feature2','workstream3','Task 3');
INSERT INTO Tasks VALUES ('feature2','workstream3','Task 3');

CREATE TABLE Jobs(
   featureId VARCHAR(50),
   workstreamId VARCHAR(50),
   title VARCHAR(50)
);

INSERT INTO Jobs VALUES ('feature3','workstream1','Job 1'); 
INSERT INTO Jobs VALUES ('feature2','workstream2','Job 2'); 
INSERT INTO Jobs VALUES ('feature2','workstream3','Job 3');

;WITH CTE AS (
SELECT distinct t1.featureId,t1.workstreamId
FROM (
select featureId,workstreamId from Tasks
UNION ALL
select featureId,workstreamId from Jobs
) t1 
)

SELECT t1.featureId,t1.workstreamId,JobsCnt,TasksCnt
FROM 
(
SELECT t1.featureId,t1.workstreamId,COUNT(t3.title)JobsCnt	
FROM CTE t1 
LEFT JOIN Jobs t3 
on t1.featureId = t3.featureId and t1.workstreamId = t3.workstreamId
GROUP By t1.featureId,t1.workstreamId
)t1 join 
(
SELECT t1.featureId,t1.workstreamId,COUNT(t3.title)TasksCnt	
FROM CTE t1 
LEFT JOIN Tasks t3 
on t1.featureId = t3.featureId and t1.workstreamId = t3.workstreamId
GROUP By t1.featureId,t1.workstreamId
) t2 on t1.featureId = t2.featureId and t1.workstreamId = t2.workstreamId

featureId	workstreamId	JobsCnt	TasksCnt
feature1	workstream1	0	1
feature3	workstream1	1	0
feature2	workstream2	1	1
feature2	workstream3	1	2

Warning: Null value is eliminated by an aggregate or other SET operation.