Too good to be true...what's the catch ?

So I have a OnePlus 5T (dumpling) that has been running Lineage16 for years.

At some point I was either too slow to keep it updated or there was no upgrade path without a reinstall (as I understood it at the time - I may have been wrong, it doesn't matter).

So...I just looked on the website and it seems I can do an in-situ upgrade WITHOUT losing data or wiping the existing install

Is this true ? Is there a catch ? I've trawled through the archives of this sub, and it seems to be true, but well, there's always a catch. What did I miss ?

Can I **really** just adb onto it a current version (22 or 23) and be on my way ?