I've been looking at the domain lifecycle lately, and it can take a couple of months after the expiration date for it to actually become available for registration. I'd check with whois on the command line.
In my case, I failed to notice the renewal notice and only realized that I missed it once the domains stopped resolving. The grace period let me avoid losing them.
I've been working on going from calendar reminders to, at least, semi-automating checking a list of expiration dates, and then checking regularly. I'm still making mistakes, I'm just trying to avoid repeating them and instead make exciting new mistakes.
For about 3 months, I checked the whois weekly. Some company was holding it. I never visited the domain in any way, to help the domain feel dead to their analytics.
Then one day, the whois result matched what you get from whois-ing a bunch of random letters with .com. It was finally released. I registered it from a company like namesilo or porkbun for the standard .com price.