What you are seeing is called the rainbow effect (RBE).

RBE is caused when using single chip DLP projectors as it shows the colors sequentially. Red, then green, then blue. It does it hundreds of times a second and most people aren't that sensitive to it.

The solution is to avoid DLP projectors and instead get a LCD projector. Epson makes some very solid entry level LCD projectors that show all 3 colors at once, so you don't get any chance for RBE like you do with DLP projectors.

Not sure what your budget is, but the Epson 2250 is a solid entry level model, and the 3800 is a fair bit brighter and offers WAY MORE lens flexibility including more zoom range and lens shift.

https://epson.com/Clearance-Center/Home-Entertainment/c/cc301#scrollTgt_onRefresh

The 880 is their most entry level home theater model with 1080p resolution. It has no zoom on the lens at all, and is very inexpensive overall at about $600.

https://epson.com/For-Home/Projectors/c/h3

There are a lot of real garbage projectors on Amazon which I would recommend be avoided. They cost less and are, in every way, inferior to what you get from a tier 1 manufacturer.

I created a search list, and you can see that all the 1920x1080 projectors on the market, under $2,000, using LCD, all are Epson models, some use a laser light source instead of a bulb...
https://www.projectorcentral.com/projectors.cfm?g=1&hide=0&st=1&exp1=1&r=13&br=2500&br=10000&c=&w=&db=&ar=Wide+%2816%3A9-10%29&zr=&wt=<g=&ll=&wr=&dt=1.0.0&mfg=&p=300&p=2000&t=&pjl=0&pjw=0&pjh=0&td=&is=&i=d&tr=&tr2=&exp5=1&oop=1&sort=%24&sz=15#list