Day 4 - Replit Tutorials broken

Question:
I’ve got a weird issue where i click on Day 4 and it’s skipped to 25% of progress. I can’t go back to the first part either, it also happens to all other days as well…

Tutorial number: i.e. Day 80
Day 4
Repl link:
https://replit.com/@willzor/day4100-days

The back arrow is missing, in which i can’t click back through the progression. I’ve cleared browser cache, tried different browsers and tried in private windows. The same issue occurs throughout.