Swiatek hasn't gone past the last-four in any tournament since winning the French Open — for the fourth time — last June, and hadn't won just two or fewer games in a match on any surface since 2019.
"I feel like I haven't been moving well," Swiatek said after her shocking loss on Thursday.
"The tennis was like on and off for most of the tournament. So I wasn't really sure what I have in my tool box. I didn't even have a plan B because nothing was working today."
The world No.2 said "everything kind of collapsed" because of her difficulties moving on the court.
"I feel like I wasn't even in the right place with my feet before the shots," she said. "I wish I would have moved better, because I think that would get me an opportunity to bounce back, because this is usually what happens."
Swiatek lost six games in a row for the second-straight day. She had recovered from losing the first set 0-6 to Madison Keys on Wednesday's quarter-finals and in her opening match in Madrid, Swiatek trailed teenager Alexandra Eala a set and a break before bouncing back.
The last time Swiatek won only two or fewer games on any surface was a 6-0 6-2 loss to Jelena Ostapenko in Birmingham in 2019.
The 23-year-old Pole said "hopefully one day it's going to click, but I'm not expecting anything, I'm just going to try to work" on trying to move better and give herself greater chances.
"For sure I feel heavy, and you are like forcing everything instead of going by intuition and by itself," she said.
Swiatek said she didn't think her struggles moving were linked to a lack of self confidence.
"No, because I felt fine today," she said. "I'm not a different player than I was for past years in terms of my attitude or my emotions."
Swiatek, a four-time French Open champion, has been nearly unbeatable on clay, according to the WTA. Only Steffi Graf (0.750) has a higher win rate against top-10 opponents than Swiatek (0.700) in the previous 35 years.
Gauff will face either world No.1 Aryna Sabalenka or in-form Ukrainian Elina Svitolina in the final, and victory for the American would enable her to surpass Swiatek and move into second place in the rankings.
