'What is going on here' is that a piece of music in F♯ minor contains a chromatic note. A normal, unremarkable, common occurrence.
As @Tim says in his answer, there is no rule that all notes/chords in a piece of music must conform to one scale.
But then @Tim's answer gets far too complicated. As do so many answers to this topic. And the complication seems to stem from a deep-seated conviction that, really, everything SHOULD conform to one scale and, when something doesn't, it needs to be justified as the key/mode temporarily changing, as a 'borrowing' (see the underlying assumption that we should always be conforming to SOME scale?) or as a daring 'breaking of the rules'.
Much music has a key centre. Not all music. Not even all rock/jazz music. But a lot of music does. And a lot of music uses functional harmonies - the sort that can be analysed as tonics, dominants etc. But even when playing the tonal/functional game, CHROMATIC NOTES/CHORDS ARE FINE!
Sometimes they're just an 'in-between' transition. Stepping on the lines between the paving stones. Same pavement, same journey, just not hitting each slab dead centre. Sometimes they're just a change of colour. The classic example is the IV chord in a major key. Often modified to iv, the same triad but minor. No excuse needed.
And sometimes a chromatic chord DOES set us off on a journey to another key, another 'home' scale. If that iv was followed by ♭VII7 and then ♭III (starting in C major that would be Fm, B♭7, E♭) there might be some use in considering it as 'borrowed' from E♭ major. But otherwise, let it be just a chromatic chord for goodness' sake!
Where did this misapprehension come from? Probably Berklee, in the 1960s. The Chord=scale thing which replaced melodic composition/improvisation with a 'this chord allows this scale' approach.
To be fair, Berklee itself admits "Using the chord-scale approach gives improvisers (especially less proficient ones) greater melodic and rhythmic mobility..." (I suggest reading the whole article)
They don't pretend chord-scale is the Answer to Life, The Universe and Everything. But it's just such an easy way to present music to a beginner, particularly one who is more fluent with chord shapes than with notation, and who sees improvisation as their primary aim rather than reading and performing the repertoire (so we're largely talking about guitarists rather than band kids :-) )
OK, rant over. But it is important to keep reminding newcomers that 'being in a key' is a framework not a restriction.