Quick update here - we took a closer look at this, and these aren’t cases that would trigger anti-cheat. Anti-cheat invokes patterns that users are unlikely to have handled (quantifiers are what we use I think), and checks if the answers are correct. Since these solutions are hardcoding patterns, the anti-cheat case doesn’t trigger – it still fails on “unknown” patterns.
We already have a mechanism to filter these kind of solutions out when displaying “Concise code examples” (more on that here: "Concise" code examples) – it looks like this wasn’t properly configured for the 3 stages in backreferences. We’re fixing this! For xe5 & Python specifically, this should already be fixed. The concise examples at the top should now not be the kind that use re.
We’ll backpropagate this to other stages shortly!