Which? Lubuntu is going through, or has recently gone through, a dynamic change.
I have been sticking with the older Lubuntu, 18.04, because I enjoy LXDE more than I enjoy LXQt.
Lubuntu was historically a distro aimed at older computers, as LXDE didn't require a lot of resources. Then, in 19.10, they made the switch to LXQt for a variety of good reasons, including forward compatibility issues and ease of integration.
So, if you're using 18.04 LTS, it's different than anything newer than it. 18.04 has support until 2023. Nobody has given me a clear answer if it's going to be supported under Ubuntu Advantage and given an extra five years of support.
And, even though LXDE is meant for older hardware, it's absolutely fantastic on modern hardware.