ayatollahsiniran, probgoingtohell and Salos are all the same person. I have good reason to believe that he is also the Reddit accounts Masashi8503 and Crank27789.

probgoingtohell posts on r/AmItheButtface (scroll to 03/10/2020)

ayotollahsiniran posts on r/AmItheButtface (see last comment on 01/01/2021)

probgoingtohell posts on r/AmItheAsshole (scroll to 01/10/2020)

ayotollahsiniran posts on r/AmItheAsshole (scroll to 28/12/2020)

Masashi8503 posts on r/NoStupidQuestions (scroll to 24/02/2021)

probgoingtohell posts on r/NoStupidQuestions (scroll to 22/02/2020)

Salos10000 posts about r/NoStupidQuestions on r/DebateAltRight (scroll to 05/02/2020)

Crank27789 posts on r/NoStupidQuestions (02/09/2021, still on Reddit)

Masashi8503 posts on r/Showerthoughts (scroll to 12/05/2021)

ayotollahsiniran posts on r/Showerthoughts (scroll to 20/05/2020)

IvantheGreat66 posts on r/Showerthoughts (14/12/2020, still on Reddit)

Masashi8503 posts on r/victoria2 (scroll to 29/05/2021)

ayotollahsiniran posts on r/victoria2 (scroll to 26/04/2020)

Crank27789 posts on r/victoria2 (09/09/2021, still on Reddit)

Crank27789 posts on r/thecampaigntrail (12/10/2021, still on Reddit)

Masashi8503 posts on r/thecampaigntrail (scroll to 28/06/2021)

ayotollahsiniran posts on r/asoiaf and r/puresoiaf (scroll to 20/05/2020)

probgoingtohell posts about asoiaf on r/DebateAltRight (scroll to 09/11/2019)

Crank27789 posts on r/asoiaf (24/08/2021, still on Reddit)

ayotollahsiniran posts on r/HistoryWhatIf (scroll to 22/05/2020)

probgoingtohell posts about r/HistoryWhatIf on r/DebateAltRight (scroll to 01/02/2020)

Masashi8503 posts on r/YAPms (scroll to 11/08/2021)

Crank27789 posts on r/YAPms (24/08/2021, still on Reddit)

probgoingtohell posts on r/TrueOffMyChest (scroll to 12/12/2020)

Crank27789 posts on r/TrueOffMyChest (18/10/2021, still on Reddit)

In conclusion:

r/AmITheAsshole: ayotollahsiniran, probgoingtohell

r/AmITheButtface: ayotollahsiniran, probgoingtohell

r/NoStupidQuestions: probgoingtohell, Salos10000, Masashi8503, Crank27789

r/Showerthoughts: ayotollahsiniran, IvantheGreat66, Masashi8503

r/victoria2: ayotollahsiniran, Crank27789, Masashi8503

r/thecampaigntrail: Crank27789, Masashi8503

r/asoiaf: ayotollahsiniran, probgoingtohell, Crank27789

r/HistoryWhatIf: ayotollahsiniran, probgoingtohell

r/YAPms: Crank27789, Masashi8503

r/TrueOffMyChest: probgoingtohell, Crank27789

This means that of 10 subreddits... and all of these accounts except Salos10000, which was probably an alt account to avoid the autoban thing that DAR users might have gotten on other subreddits have posted in r/TNOmod:

ayotollahsiniran posted in 6/10 (+ r/TNOmod = 7/11)

probgoingtohell posted in 6/10 (+ r/TNOmod = 7/11)

Crank27789 posted in 6/10 (+ r/TNOmod = 7/11)

Masashi8503 posted in 5/10 (+ r/TNOmod = 6/11)

Salos10000 posted in 1/10 (but he admits in YORAMRW's thread to being probgoingtohell)

Ask yourself what are the chances of three accounts posting in seven of eleven subreddits and another account posting in six of eleven subreddits not being the same person? Ivanthegreat66 also uses the 'Yous' thing like all of the others I've mentioned, which is why I've chucked that one in despite having less evidence.