This is where I try to explain that I saw a UFO yesterday, late afternoon, broad daylight.
It was moving around, this way, that way, not straight flight, but seemed to be able to maintain altitude that averaged 4,000 ft.
Weather was partly cloudy in some sections of the sky.
The UFO slowly made its way, westbound, at a speed of roughly 1 mile per 15 minutes. No sound.
Looked like one of the undersea, amoeba shaped creatures.
About 80 feet long x 30 ft wide.
Might have been a research or weather balloon.
Back in the '60s I was a small part of a team that flew instrumentation packages to 100,000 feet and above on the famous "skyhook" balloons.
https://en.wikipedia.org/wiki/Skyhook_balloon
One time we had a launch malfunction. The balloon was cut loose at ground level without the load, and that loose balloon looked just like that, although a lot bigger. I had an 8mm camera running and caught it on film, but after 60 years I'm sure that clip is lost.
There are a lot of weirdly shaped Mylar balloons out there - from your description I doubt what you saw was anything more than a balloon.
When you see a real one, you will know.