You're renewing improperly--you'd ordinarily renew the cert after about 60 days, not once it expires.
No, Let's Encrypt certs are only valid for 90 days. If there's any change on this, it would be to an even shorter lifetime--there was talk of this early on, but I haven't seen any discussion in the last couple of years.
This is a subject that's gotten a lot of discussion in the past; the canonical topic is probably this one:
See also:
Edit: But it's kind of interesting, browsing through the first of those (5+-year-old) topics and comparing the situation to today. My router supports obtaining certs from Let's Encrypt automatically. So does my NAS. So does my hypervisor. A great deal of server software, in fact, has support for Let's Encrypt built in. My Mikrotik network switch doesn't, but I have a script that automates deployment to that. My 3D printer doesn't, but it's a simple modification. Whatever my concerns about certbot, its renewal features work quite well. For all the complaints there about the automation, it's actually working quite well.