I have an Asus RT-AC1200, released in 2019 that hasn't had a firmware update since 2021/05 which is the reason why I bought the TP-Link. I do see Asus has a Nov 2024 firmware for that RT-AC68U on their site.
As far as my TP-Link router, I think I remember it being stuck on a 2022/09 firmware until at least 2023/09, and I wound up flashing it with OpenWRT earlier this year.