I had only one interview step: a Skype call involving solving algorithmic problems.

Indeed did not conduct the interview itself; it delegated it to Karat, a firm specializing in interviews.

You had one hour and needed to solve at least three problems.

You had a second chance within seven days before your interview results were reviewed by Indeed, if you felt you did not perform well the first time.

Very easy, something like LeetCode's "easy" level. However, you should compile, test, and run each problem during an interview. Solving only one or two problems isn't good enough for the next interview steps.