The timeline details are correct, with it being that you're misreading them. For testing purposes, and to confirm my interpretation, I just unaccepted and then reaccepted my answer, with the timeline originally just showing one entry of the acceptance, but with it now showing an earlier set of $2$ entries. In particular, consider your answer's timeline shown below:
Each group of $2$ "accept" entries have $2$ date/time values, and are shown with a pink background, I suspect to indicate that they have cancelled each other and, thus, are no longer applicable. I believe that having the second entry with an action of something like "unaccept" would make this more clear, and likely also less confusing.
Since it's shown in reverse time order, starting from the last set of values, note your first one shows the OP accepted on July $15$, $2023$ at $0$:$11$:$01$Z (the $01$ seconds part is seen by clicking "toggle format" or from the tooltip), then the one just below it shows the OP unaccepted your answer just about $5$ seconds later at $0$:$11$:$06$Z. The next set of values up shows the OP accepted your answer again about $3$ seconds later at $0$:$11$:$09$Z, but then unaccepted again about $3$ minutes after that at $0$:$14$:$09$Z. Finally, the top set of pink entries shows the OP accepted your answer once again just about $1$ second later, i.e., at $0$:$14$:$10$Z. Note the total time period between the initial acceptance and the last acceptance described here was only just about $3$ minutes and $9$ seconds. Thus, unless you were online then, it's quite possible you didn't notice the multiple times your answer was accepted and unaccepted. Also, your reputation listing would likely condense these into one entry of $15$ points for the acceptance whenever you checked it afterwards.
Note that your answer remained accepted until April $2$, $2024$ at $23$:$54$:$24$Z, i.e., about $14$ hours ago. In your question's timeline, the current top entry (note it has no pink background, and is shown by itself, which means it's currently valid) indicates the OP has accepted another answer at $23$:$54$:$24$Z, i.e., almost immediately after unaccepting your answer.
