An interview with Moncet who which gives us more details about Tänak's departure (I'm quoting Estonian site which is quoting some French news site)

https://sport.delfi.ee/artikkel/1200...kumise-pohjusi

*Tänak let Hyundai know before the RACC
*Tänak weighed his decision for a very long time
*Tänak was very resolute and there was no chance changing his mind. Didn't give any concrete reasons and said the same thing that he is at a stage of his career where he needs to embark on a new challenge.
*Tänak wasn't easy to work with but he was very demanding and detail oriented, wanted to understand everything.
*Doesn't know what will Ott do and Hyundai's driver options depend on what he will do next (if he doesn't retire)
*At the moment Moncet rules out that they will continue with only one driver who is doing a full season.