Unable to extract tar.gz: is a corrupted tar file (checksum mismatch of file "7zXZ")

I’m using PharData to extract a tar from a tar.gz file.

I am grabbing the tar.gz from a reputable source via an API which is widely used, so it’s unlikely to be a corrupt file. I have tried several files with the same outcome.

When attempting to uncompress the .tar.gz file I am given the exception:

   [UnexpectedValueException]   phar error:
 "C:/xampp71/htdocs/suite/storage/app/websites/2/2017-08-30/boo/json-1.tar.xz"
 is a corrupted tar file (checksum mismatch of file "7zXZ")

There is little information out there about this. If I open the file in a plaintext editor I can see the first few characters contain 7zXZ:

ý7zXZ  æÖ´F !   ÿçì èÿõ7] 2Iâ#¶ò¢ÝÕž~çVûáä“Uùx].íÖaÕ–~–óаâÖ-¨e L»ÎÓð+Òø7(Êf9R‰Æ³   ö¤`W’5T˜"ªÕÌ®ûJ©ú EüxC'Îà-ÃVÀ›Fòïžäë&n°I¨ÚŸsƳç!¾lÒT¾:FÕÇ8Ϻ·úöbX‡$¿‰`Õê[v}9R€ÊÌìK°ŽÖÙÜßN~VêÓ‘e’cŽ¼^:©!S¸°o¯ošÞwöhƒ^åPH¸™O§Õ |-c_ò܇§švîëÆ0ŠÞR”Z% %Üê´?ýé6Ê#v/ñ½/›û?LæÌCÏL‡lÍN…Ûõ“áƒO-«gË*¥RÙÌ.o´›s¨e_ážàh,<¾
¼wñØ—œu²sÁÏ0¥ìéõš¨t”8õôQú®¯þß!Bš£Þ5š}P|ò§å•ˆ
,‡¸¦U245)Ù®f†íB%Œ•Ú¸±¡Á@
‡‰»€è×é/(lÍVÔ&¦g²,dõàBÔéâylÅ<Ášs«¢`Ék.Åøù+º’o>zkm´8à%eçÍÒ.BúÝHÜÿ

I am able to open the archive using a local app such as 7-zip.

Any ideas?