The pasuk in Devarim itself supplies the textual basis for the user's observation: Moshe states that God was incensed with him specifically "because of you" — that is, on account of the people's sin — saying he too would not enter the land (Devarim 1:37), with no mention of Mei Merivah.
The Malbim (Devarim 3:26) reads these words as evidence that the original, root decree against Moshe's entry was issued at the time of the spies, arguing that once Israel sinned with the meraglim they were no longer fit for Moshe to lead them in, and that the episode of Mei Merivah only transformed what had been a conditional decree into an irrevocable one sealed by oath.
By contrast, the Ramban (Devarim 1:37) reads "because of you" as pointing squarely to the sin of Mei Merivah — the people's strife caused Moshe and Aharon to strike the rock rather than act as commanded, and the phrase בִּגְלַלְכֶם echoes the language of Bamidbar 20:12, where God explicitly tells Moshe and Aharon that their failure to sanctify Him before Israel is the reason they will not bring the congregation into the land.