I changed from blau.de to fraenk = Telekom in disguise today.
Originally I wanted to get Lidl or Aldi Prepaid but I didn't want to leave the house and do the whole identification stick and searched for something with e-sim and online identification where I don't have to talk to anybody.
Worked fine so far but now I need to wait 10 days until my old phone number gets transferred there.
Would have expected it to be cheaper tbh.