I fixed your image. You need the image link, not the album link, to use the Imgur BBcode. Just the letters after the / and the .png, .jpg, .gif, etc. need to be added, rather than the full url. This thread might be of some help: How to, Upload an Image
To answer your question, I would assume the rise was primarily due to that DXP Weekend being unexpected. It came very soon after the previous one, and it was the third for 2018, while there are usually only two per year.
Players usually have more time to stock up between DXP Weekends, but this one came suddenly, which caused a steeper rise in price as players rushed to stock up on supplies. Had this DXP Weekend not happened, the next one wouldn't have been expected until the end of February or early March 2019, based on previous years.~ Sicariu
Well i had like 100k of zammy wines that i bought for 7.5k ea approx after last bxpweekend. Thinking i had a good deal, they dropped to like 5.5k and only went up to 7.5k max a week before the unexpected weekend. Now im still stuck with them wishing i sold for 7.5k then but we always wait for more ;p oh well