Few months back, skype wasnt staying alive on my android phone(s) Eventually found out it didnt have the "Show skype as an ongoing notification" setting. So I installed an older version, and Voila!!, Fixed.
Now its Forcing me to update. or Forced signout if I dont. Making it unusable without updating.
But I tried an even older apk version I had from 2015. I ticked "Dont Show Me This Again",(The Update) and then Continue!
And,... Voila!! Im back. Versions 18.104.22.16847 & 22.214.171.124715 both work. Im happy to send anyone the apk who wants it. (If Im allowed)