The new suits have significantly increased the percentage of record breaks. Some would have been broken even without the suits, but many have been broken that wouldn’t have been without the use of the new suits.
some I have seen the participants were not wearing the suits. Like the 4×100m there where 5 teams over world record time and not all the teams had the suites
The suit linked to the increased rate of broken world records is the Speedo LZR Racer. It the most hydrodynamically designed suit ever developed (by NASA). The suit is made of high-tech material the actually repels water and reduces drag signficantly because it lacks seams (ultrasonically welded). It also increases oxygen efficency and reduces skin vibration because it grips your body so tightly. Already some times have been reduced by almost 5 seconds, which is unheard of in swimming. Mixed with it being an Olympic year, these eye-popping times that are being recorded are only the beginnning.
Oh, there are also other changes as history goes, they can now dolphin kick under water past the flags, they can roll over to flip turn for back stroke. You couldn’t do that when I swam in 87. All these little things add up.