Long story short, got a borrowed bIII chord and did a relative change to Phrygian, and now said chord (Eb) appears as a bI. Now, that’s just how Hooktheory works out that chord, but why does it appear as it was borrowed from “bor”?
My question is: What is this “bor” thing?
“bor” stands for borrowed. As Hookpad is a tool to learn music theory we try to point out the connection and functionality of each chord you write.
As every key has only 7 native chords every time you need another chord in Hookpad you have to “borrow” it from another scale. In pop music those scales usually are not that far away as the might have the same root note. So for example if you’re in C major and you want to play a F Minor chord you can just borrow it from the C minor scale.
In your example you seem to be in E minor so there is no close scale to build an Eb major chord from so Hookpad borrowed it from an Eb lydian scale. If you’d have searched for D# it would have borrowed it from the V of the three of the E major scale.
Lots of music theory involved here. Please let me know if this was helpful.
Ah. I see now, thanks for clarifying! 
Thank you for your answer but I have another question related to your answer : if the Eb major chord is from the lydian scale, why is it written “bor” instead of “lyd”?
If it’s borrowed from a scale with the same tonic, then the mode of that scale is listed. Otherwise, it just says (bor). If
Here’s an example in C major:
The D chord is listed as borrowed from C lydian because that’s the only C scale that has C, D, F#, and A.
The C# chord could be from C# lydian, but it could also be C# major or C# mixolydian. Without more context, we couldn’t say, and also it doesn’t really matter.
