This is my profile picture.
Why does it show in my reputation on top I got 30 points today. But at the bottom of the page it shows 28 points?
There's two different forms of reputation tracking going on that's being shown to you.
The first is your reputation page, which shows your change over the course of the day from the previous day's end. This thing just tells you every event that affected your reputation from the perspective of changes from yesterday's value. In this case, you gained 28 reputation in total from new accepts and upvotes. You also moved an accept vote from one answer to another. You "lost" 2 rep for that, but regained it because you still have an accept. This still resolves to 28.
The second is on the dropdown, which speaks of reputation changes on an event level. This may sound weird, so bear with me. The original acceptance you made was on January 28th. Removing the acceptance, in the system, is not a matter of subtracting two from your reputation score. Instead, what happens is that we remove the original +2 from back in January. Then you accepted a new answer, which since that happened today, it shows up as a +2 for today. Since today's event tracking doesn't include the previous acceptance (since that was back in January), it shows a +30 for today right now. On an expanded level, this behavior is also reflected when upvotes and downvotes to your posts are removed.
This probably has roots in the fact that, prior to the implementation of the new reputation timeline, all forms of visible reputation tracking were of this later, event-level method. The dropdown at the top was from back then and we never updated the display to reflect this.