Hi.
OK the answer here is long and complicated.
Please read here first.
There are a number of bugs on this as well - you should always check these things in the release notes and Issue before upgrading.
However, with the recent growth of Rocket.Chat there have been discussions about whether we should either drop support completely, or continue it. This has not yet been resolved so I have no definite answer here as yet but I am hoping it will be resurrected, though I have no idea on timescale.
I would suggest you +1 an existing bug, or open a new one… it may be closed as a duplicate but will register the point.