Accounts keep disappearing? (iOS)

Twice now in the past 6 months I have gone to comment or upvote and it asks me to log in or create an account. My accounts have literally always been hooked to my email and I haven’t received anything saying “you did something wrong” just one day I have an account and the next I don’t. My several year old account u/mattlyn13 went first after having no problems using Reddit on mobile or desktop for years. Then I created a new one, u/chance-weather-555, and it was gone within like two months. When I go to create a new account it lets me use my email that I have used for all of them, but won’t let me log into them with my email or password and also says the usernames already exist so I can’t use them again. Any help would be lovely. I would love to have my original account back or at least for my accounts to stop being deleted.