I saw that in Uzbekistan as a deployed US military in 2003-04. Uzbeks told me that under USSR thirty percent of the population in Uzbekistan was Russian and it was already down to less than seven percent by then. And nearly one third of Uzbeks were now in Russia working.
But I met Uzbeks who converted to Christianity and they said most Uzbeks are not serious Muslims and hate Afghanistan. I watch Uzbek videos on youtube and it is like you say a very complicated picture, there is more nationalism than Islam in the comments.
The Uzbeks I met spoke English and Russian besides their own language so maybe they are the educated class. But everyone admired Russia and Russian food & music. They also say there is close kinship with Turkiye and Uzbekistan, many said one parent was Turkish.
Interesting part of the world and Uzbeks have computers & cell phones so they know what is going on elsewhere. Islam Karimov is a dictator but not as bad as the mullahs that’s for certain.
‘Russians’ are actually a term they are using to name every non-Uzbek caucasian minorities. Most of them are Russians and Ukrainians, a lot are actually Germans. Jews considered Russians as well.
As for nationalism and Islam it is always hand by hand in this part of the World.
‘Russian’ population couldn’t decline that much naturally there, I think you understand it.
And they don’t have to be all serious about Islam to make things ugly. It is enough to have 10 in 100 jihadis. BTW, don’t be naive to belive everything they are telling you on their feelings about Afghanistan and Islam. Lying to strangers is a part of their traditions. There are numerous Uzbeks in Taleban since 80s.