Thats likely due to lack of algorithms with goal to keep you browsing forever. Twitter likely harvests all the data it can get from you when you browse twitter. They can also track your browsing habits using your IP (among many other things) and sites that have embed twitter content like share button or embed tweets.

Just look for the things that you are interested in. That's how i accumulated many of my followed accounts over time as well as subscribed subreddits over time.

You can also look for users under the same name on Mastodon and (hopefully) find them.

Please note that if you find an account you also followed on twitter and it ends with @bird.makeup, it's a bot mirroring tweets on Mastodon without mirroring your answers on Mastodon back to Twitter.

I also didn't understand how to do this in Twitter. Tried twice, didn't succeed. At least, now I don't miss it.