Just ask it to figure it out step-by-step and to remove accents:
GPT-4:
Figure this out step by step and check your work:
Remove the accents and tell me if this a palindrome: Élu par cette crapule
GPT-3.5 (Needs to know that removing spaces and lowercasing is okay):
Figure this out step by step and check your work:
Lowercase it and remove the accents and spaces and tell me if this a palindrome: Élu par cette crapule
GPT-4:
Figure this out step by step and check your work: Remove the accents and tell me if this a palindrome: Élu par cette crapule
GPT-3.5 (Needs to know that removing spaces and lowercasing is okay):
Figure this out step by step and check your work: Lowercase it and remove the accents and spaces and tell me if this a palindrome: Élu par cette crapule