ST_Minkowski offset/translation issue or user problem?

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Testing the ST_MinkowskiSum is producing an unexepected translated position. for the geometry. Is this expected?

oid    |extname       |extowner|extnamespace|extrelocatable|extversion|extconfig|extc
-------+--------------+--------+------------+--------------+----------+---------+----
  13745|plpgsql       |      10|          11|false         |1.0       |NULL     |NULL
  79944|postgis       |      10|        2200|false         |3.2.0     |{80254}  |{"WH
  80982|mobilitydb    |      10|        2200|false         |1.1.0     |NULL     |NULL
3694605|postgis_sfcgal|      10|        2200|true          |3.2.0     |NULL     |NULL



WITH T(id,trip) as (
  SELECT  	        1,setsrid(tgeompoint '[Point(1000 1000)@2012-02-01T00:01:01, Point(1020 1010)@2012-02-01T00:01:02, Point(1040 1020)@2012-02-01T00:01:03]',3857)
  union all SELECT	2,setsrid(tgeompoint '[Point(1100 1000)@2012-02-01T00:01:05, Point(1120 1010)@2012-02-01T00:01:06, Point(1110 1020)@2012-02-01T00:01:08]',3857)
  union all SELECT	3,setsrid(tgeompoint '[Point(1200 1000)@2012-02-01T00:01:10, Point(1140 1010)@2012-02-01T00:01:20, Point(1160 1020)@2012-02-01T00:01:40]',3857)
) 
select
  ST_AsEWKT(ST_Force2D(t1.trip::geometry)) as wkt_t1geom,
  ST_AsEWKT(ST_Force2D(t2.trip::geometry)) as wkt_t2geom,
  ST_AsEWKT(ST_MinkowskiSum(ST_Force2D(transform(t1.trip,3857)::geometry), ST_Buffer(ST_Force2D(transform(t1.trip,3857)::geometry),10)))
  --ST_AsEWKT(ST_MinkowskiSum( transform(t1.trip,3857)::geometry, transform(t2.trip,3857)::geometry ) as wkt_mink
FROM T t1, T t2
where t1.id < t2.id


wkt_t1geom                                         |wkt_t2geom                                         |st_asewkt                                                                                                                                                                                                                                                      |
---------------------------------------------------+---------------------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
SRID=3857;LINESTRING(1000 1000,1040 1020)          |SRID=3857;LINESTRING(1100 1000,1120 1010,1110 1020)|SRID=3857;MULTIPOLYGON(((1990.0251579118735 1999.2911097990932,1990.3551193231879 1997.358735770496,1991.0557280900007 1995.5278640450006,1992.1000602103095 1993.8688539962527,1993.4479825863987 1992.445460450043,1995.0476953172788 1991.3123836221034,1996|
SRID=3857;LINESTRING(1000 1000,1040 1020)          |SRID=3857;LINESTRING(1200 1000,1140 1010,1160 1020)|SRID=3857;MULTIPOLYGON(((1990.0251579118735 1999.2911097990932,1990.3551193231879 1997.358735770496,1991.0557280900007 1995.5278640450006,1992.1000602103095 1993.8688539962527,1993.4479825863987 1992.445460450043,1995.0476953172788 1991.3123836221034,1996|
SRID=3857;LINESTRING(1100 1000,1120 1010,1110 1020)|SRID=3857;LINESTRING(1200 1000,1140 1010,1160 1020)|SRID=3857;MULTIPOLYGON(((2190.0251579118735 1999.2911097990932,2190.355119323188 1997.358735770496,2191.055728090001 1995.5278640450006,2192.1000602103095 1993.8688539962527,2193.4479825863987 1992.445460450043,2195.0476953172792 1991.3123836221034,2196.8|

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