covid 19 – Quarantine protocol when reaching small airports in Germany from main airports

I have to travel soon to Leipzig (Germany) from Dublin (Ireland), and most flights (from Lufthansa, KLM, Ryanair) either go to other bigger airports (such as Frankfurt, Berlin, or Dresden) or go to these and couple them with a train to Leipzig.

As of May 21st, Dublin is still a risk area for most German states, so I would have to quarantine when I arrive there. However, I am having trouble finding any information on whether they allow for taking an ICE to another airport, which (it seems to me) would completely defeat the purpose of a quarantine upon arrival.

Does someone know where to find information about this, or what the current protocol is? Would I have to find a direct flight to Leipzig?