pulling from a repo is causing merge conflicts with 8 year old files, despite regularly pulling from this repo

Question

Context

I am developing alpha.

alpha is a clone of beta (not a fork).

beta is an ever evolving project that I am tracking.

Problem

Once a month, I run git pull beta master to get the latest changes and updates. I last successfully did this 26 days ago.

Yesterday when I ran git pull beta master, I started to get merge conflicts that originate from a commit in 2015.

Goals

• Pull all the updates to beta master in the last 26 days
• Pull from beta master in the future without issue.

Questions

I do not know how else to debug or troubleshoot this, and I'm hoping somebody can answer:

1. Did I do something to alpha that would cause this to happen? If so, how can I fix it?
2. Are there things on beta I can check to see if this on their end?

Troubleshooting

1. I cannot just deny the incoming conflicts - my project is completely inoperable due to the changes that are made by the files that successfully merged without conflicts.
2. I have tried reverting my repo back 100~ commits and THEN pulling from beta, and the same problem occurs.
3. I am a contributor to beta, and me (nor the other contributors) can see anything that changed on beta that would cause this.
4. This also happens when I cherry-pick any commit from beta.

Answer 1

I wasn't explicitly telling it to rebase but when I ran git pull --rebase=false, I got was I was expecting. No idea how that happened, but glad its resolved now.

I would love if somebody was able to explain how this happened in the first place, so that people googling in the future that find this, can avoid the pitfalls.