@kartik yes, as of now we had to reduce it ~2.5 years. IMO both Framework and ERPNext are maturing quite well, so we’ll soon start providing LTS versions. V13 has had a supported life of 2.75 years.
As of now supporting more than 2 concurrent major versions is becoming quite a problem for us. Especially because of large refactors from v14/v15.
v13 also was built on top of system dependencies like python 3.6, MariaDB 10.3, NodeJS 12 which are all already EOL or nearing EOL. So it’s not wise to keep supporting this version.