Veigar
removing hialgo did not remove compression in the game, reinstallation did not help
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QuiteReluctant
Some users had this problem a long time ago... Search this forum for "uninstall", and find the case similar to yours. For example:

https://hialgo.forumchitchat.com/post/all-supported-games-permanent-potato-quality-even-after-uninstalling-hialgoboost-9970700?highlight=uninstall&pid=1307036579
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