That's what I thought. So for whatever reason the OP chose to install Knots instead of Core. Hope it was out of ignorance of Luke's evil plan...
Still puzzled that Knots did not by default signal RDTS support. Considering Knots is already censoring his blocks it makes no sense for it to not broadcast RDTS support from the gitgo. Leave it to Luke to let it run like that and then as Consesus day approaches make Knots stop with no message popping up as to why...
With luke you never know. Could just be another bug that knots introduced.
Did another quick check, if you go to install a pool with umbrel it asks you what back end node you want to use

So the OP had to choose knots. Why they did unless they tell us we will not know.
But, unless he changes to a supported node it's going to stop mining in 1073 blocks from when I made this post.
It's the internet, we are not your mom, we can give you advice but can't make you take it.
-Dave