Short text winning over images tracks with what I've seen lately, the platform seems to be throttling image reach pretty hard right now. What helped me was treating the text post as the hook and dropping the visual or link in the first comment instead of the post itself, reach held up way better that way.
One thing I'd add though, dont just look at raw engagement numbers. Check what kind of engagement it is. Short text gets quick replies but a lot of it is low intent... people typing "this" or a one word reaction. If your actual goal is traffic or conversions that vanity number can be misleading. I had a page last year that crushed it on comments but the click through was garbage.
@WindSpace Agency what were you optimizing for across those 3 pages, just engagement or were you tracking clicks too? changes the answer a fair bit imo.