expression, noun-modifying (irregular)
same as always; unchanging; usual
Fixed prenominal expression meaning that something remains exactly as it always has been, often with a nuance of mild exasperation or resignation. Used before nouns.
彼は相も変わらぬ笑顔で迎えてくれた。
He greeted me with his usual, unchanging smile.
相も変わらぬお忙しい毎日をお過ごしのことと存じます。
I imagine you are spending your days as busy as ever.
相変わらず is the adverbial form ('as ever, still'), while 相も変わらぬ is a prenominal adjective ('the same old...'). The も adds slight emphasis.
Derived from 相変わらず (as ever) with the classical negative ぬ replacing ず, and the emphatic particle も inserted. The expression fossilized as a prenominal modifier.