Good question, and the short answer is: it can matter, but it is usually manageable rather than disqualifying.
Note buyers care about two things tied to this situation. The first is seasoning on the note itself, which you already know about. The second is seasoning on the seller's ownership, sometimes called "vesting seasoning" in the note space. The concern is that a recent acquisition, especially through a non-arm's-length transfer like a probate deed, raises a question about whether title is clean and whether the seller had full authority to convey. Eight months is on the shorter side, and some note buyers have informal thresholds around six to twelve months of seller ownership before they will buy a note.
A personal representative's deed (the document a court-appointed executor uses to transfer property out of an estate) is a recognized instrument and not inherently problematic. The real question is whether title insurance was issued when your seller took title and whether it will be issued again at closing for the new buyer. If your seller has a clean owner's policy and the buyer will get a new owner's policy plus a lender's policy protecting the note, most institutional note buyers will be satisfied. The policy addresses the "what if something was missed in the probate process" risk.
I would not assume any note buyer will treat this identically though. Ask two or three note buyers before you close, not after, because their appetite and pricing will tell you whether the discount on the note is worth the structure you are building.
I am not a title attorney, and this situation is close enough to a title question that I would run it by one before finalizing anything.
What is the loan-to-value you are planning on the note? That number changes the conversation with note buyers as much as anything else here.