Maybe they have an algorithm that knows exactly what to do to enhance smaller images? I remember someone on here talking about having to resize in several steps and sharpening each time for best results.
I am trialing a free site called https://postimages.org - put a trial in the test zone and all seems ok so far. It will only let you do 12MiB image size though. Didn't read the fine print however.. so..... waiting for the world to end or some such.
Photobucket as you know...put an ugly watermark of its own on your images.
There are some suggestions here... https://thetechreader.com/top-ten/18...s-and-ratings/
When I get more time I will give some of them a shot.