@stitch makes a good comment here. Think D# not Eb.
First up here is an mp3 audio sample of the main intro riff simplified and played without the octave repeat of the root note for each chord so you are hearing just two notes for each chord. Plus, I have taken the liberty of adding a full E major chord at the end to give it a definite resolution to the tonic.
Love Yourself Intro Riff mp3
Next, here is a tab of the same simplified version.
If we are happy that E major sounds like home and continue by working on the basis that this is in the key of E major.
E major scale
E, F#, G#, A, B, C#, D#, E
Harmonised E major scale
E, F#m, G#m, A, B, C#m, D#dim
Chord tones & formulae
E = E, G#, B = 1, 3, 5
F#m = F#, A, C# = 1, b3, 5
G#m = G#, B. D# = 1, b3, 5
A = A, C#, E = 1, 3, 5
B = B, D#, F# = 1, 3, 5
C#m = C#, E, G# = 1, b3, 5
D#dim = D#, F#, A = 1, b3, b5
Now taking just those in the intro riff.
E = E, G#, B = 1, 3, 5
F#m = F#, A, C# = 1, b3, 5
C#m = C#, E, G# = 1, b3, 5
D#dim = D#, F#, A = 1, b3, b5
Compare the chord tones with the tab.
Chord 1
This can be seen and heard as E major though it is just the 1 and the 3 (no 5th).
Chord 2
This can be seen and heard as D# minor though it is just the 1 and b3 (no 5th).
Chord 3
This can be seen and heard as C# minor though it is just the 1 and b3 (no 5th).
Chord 4
This can be seen and heard as F# minor though it is just the 1 and b3 (no 5th).
There is a clear and obvious pattern. These are all chord ‘fragments’ and none has the 5th.
Turning our attention now to just the chord being questioned - the D# minor chord. Or is it a D# minor? It has only two notes (again, a reminder, I simplified and removed the octave repeat of the root note in my transcription). Those two notes are the root and the flat 3rd. The lack of any 5th means the actual nature of the chord is ambiguous. It could be a plain and simple (and very diatonic) D# diminished chord or it could indeed be a D# minor chord. Replacing a diminished chord with a minor having the same root does work in some instances (as @stitch has stated above) and involves just one note being replaced effectively. If the minor is played without its 5th then no non-diatonic note is being introduced whatever.
It is impossible in this song example to say whether the chord is truly D# diminished or D# minor unless other instrumentation comes in and plays either the note A (diatonic, making D# dim) or the note A# (non-diatonic making D#m).
The direct question about borrowing would require quite some explanation beyond this point. If the D# root chord is D#m then it is possible to create a line of argument that it has been borrowed not from the relative key of E minor, but by use of modal interchange where it could be seen as borrowed from any or all of E Lydian, E Phrygian or E Locrian. If you really want it I will go through that thinking but am inclined to leave it unless specifically requested.
I hope that makes sense.
Richard