I don't understand how people say it's the same speed, especially after watching the video. The video claims that BF2042 has a sprint speed of estimated 7.4m/s, and BF4 of 6.5m/s. That's an increase of 13.8%, which by all scientific standards is a significant difference. Add to that slide and tacsprint spamming, and there's no doubt that BF2042 is way faster. Luckily, slide spamming was addressed by DICE already (don't find the link right now).
Edit: Here's u/lytlb1t's comment about sliding uphill, which I think already solves some of the perceived issues: https://www.reddit.com/r/battlefield2042/comments/q385w0/comment/hftwyut/
Btw. I recommend everyone to read the thread that I just linked to. u/lytlb1t gives many excellent and insightful explanations. If I could wish for anyth...
Regular sprint speed is the same as bf4, tac sprint is slightly faster, but still the same as bf4's sprint with some top speed perk (can't remember the name right now). So in the end the movement is not faster, but yes there are different factors why it is perceived as such.