I see this was discussed also in #10292, in comments 1, 2 and 3.
I will copy the solution here, for search-ability:
Asias:
First, when a node is unreachable. It is much better to run the replace a dead procedure than running removenode. When more than one nodes are down, you can use ignore_dead_nodes_for_replace option to ignore the peer down node when running replace. With replace, you can add 2 more nodes back.
jarPotato:
I tried replace node procedure with the two config params you mentioned, but faced an error that looked like #13865
But debugging that issue nudged me towards the Raft manual recovery procedure guide, using which I was able to recover my cluster! (removenode worked when all UN nodes where in recovery mode)Thank you helping me out @asias!