I assume you built things in questionable ways because as you said, the company was growing like crazy and there was no time to “do things right”. It just had to work. It sounds like you did a great job if the company is currently doing well.

My only advice is you should be open-minded to the newer devs who work day-to-day with the “legacy” systems you originally wrote and may have very informed ideas about how to improve or refactor those systems. It’s not a knock on you, the company is simply in a different stage.