I made my own log in and registration for my game using php and unity.

Players could register an account and it would save to a mysql db, and I like pulled data and updated game stats etc.

Took me like 6 months the first time, and hard frustrating, back breaking work and for basic sql shit took 3 days the second time.

In fact, I did it without AI assistance in like 2021, and then redid it with AI in late 2023. Stark improvements, not only time but injection protections, spam filtering (like offensive names) and other cool shit.

I suppose it was easier because I suffered.