Are you aware that you've been running a version that hasn't been getting updates since July of last year? If not, then having your OS actually get updates again might be a surprise. You'll have to update to 20.04 first, though, and then 20.10 before you can update that to 21.04. There's no direct update path (another known surprise, one might say). If you don't want to update every six months, just stick to the long-term support version (LTS, currently 20.04).
The bootloader was broken for this laptop model in 19.10 and I've been deferring going through the same pain upgrading to 20.04. Totally aware of the support situation and upgrade sequence, but an unsupported machine sure beats a bricked machine
Only every second xx.04, to the best of my knowledge. 20.04 was an LTS release, the next LTS will be 22.04. 21.04 is a standard release supported for 6 months.
Edit: Ninja'd by jpace121, should have refreshed before commenting.
I don't run Ubuntu. If I did, your question has convinced me I would be happiest on an LTS version. 5 years of not changing much is more in line with my level of interest in puttering around my OS settings than every 9 months.
The 19.10 bump was to get some fresh base libraries to build something as I recall. I think it might have for Remmina. Otherwise totally agree with you, LTS is always preferable