This is actually an issue that may be affecting more and more people buying their first telescope. A few years ago multiple sellers on eBay flooded the market with cheap no-name reflecting telescopes that had short tubes. There’s nothing inherently wrong with short tube telescopes, in fact they can be great for beginners as they tend to have wider fields of view. ( Because Short Tubes = Lower mangifications = Wider fields of view = easier to find objects in the night sky!).
Unfortunately all those cheap telescopes with short tubes had a big shortcoming – they all had Spherical Mirrors in them instead of the more called-for Parabolic Mirrors.