chord extensions

hi guys, the other day I was with an alternate bass teacher for my lesson and he taught me this real pretty dominant chord and I don’t remember the shape or voicing or ynothin. :( can yall give me some possible recs for what this coulda been?

A friend of mine has recently started studying guitar and so has been asking me questions about music theory. His last question surprised me a bit. He asked something like: "Regarding chord extensions and borrowed chords, is there an upper limit where one can exceed good taste?" I responded...