Debug log which I turned on recently:
2019-01-16 12:59:36 6181 -> SCHEDULED at Wed, 16 Jan 2019 12:02:00 +0000 (1547640120) with options Array ( [expireType] => category-add [id] => 6181 [category] => Array ( [0] => 18 ) [categoryTaxonomy] => category )
2019-01-16 02:31:14 6100 -> SCHEDULED at Thu, 10 Jan 2019 12:42:00 +0000 (1547124120) with options Array ( [expireType] => category-add [id] => 6100 [category] => Array ( [0] => 18 ) [categoryTaxonomy] => category )
2019-01-15 15:11:10 6140 -> SCHEDULED at Tue, 29 Jan 2019 23:01:00 +0000 (1548802860) with options Array ( [expireType] => category-add [id] => 6140 [category] => Array ( [0] => 18 ) [categoryTaxonomy] => category )
2019-01-15 15:11:10 6140 -> EXISTING FOUND – UNSCHEDULED
2019-01-15 15:10:54 6140 -> SCHEDULED at Tue, 29 Jan 2019 23:01:00 +0000 (1548802860) with options Array ( [expireType] => category-add [id] => 6140 [category] => Array ( [0] => 18 ) [categoryTaxonomy] => category )
2019-01-15 15:10:53 6140 -> EXISTING FOUND – UNSCHEDULED
No categories are added to expired posts. Not sure if you need more info?