[rootusrootus]

My understanding is that afterburner flame color mostly comes down to temperature. American jets have blue afterburners, too, at lower power levels, it turns orange towards the upper limit. Maybe Russian jets typically have the maximum dialed down, or that's just the limit of the particular design. I know that it is (or was, at least, 30 years ago) pretty common in the US for Air National Guard fighters to have stops installed when they're training, and not on alert status. IIRC they were typically capped at zone 1 (out of 5 available)[0]. Barely visible at all.

[0] That's 30 year old memories right there, take with a heaping spoonful of salt. I used to know a fighter pilot in Portland flying F-15s and learned a lot about their operations. But memory fades...