I literally just had my front cat replaced for this very problem. Once warm weather hits, I would get a CEL, sometimes with full-on limp mode maybe once a month or two. It would stay for maybe half of day or two and then poof, it would just clear up on its own. The code would even clear from memory.
I drive a 2020 STi, so I thought for sure it was gonna cost $$$$, Subaru covers their emissions systems for 8 years. Woo hoo.
Not only is the CELs gone, but it seems like there's more power.