Here's a new one I found related to cover & stealth: pg. 451 says half and three-quarters now also grant their +2/+5 bonuses to "...ability checks made to hide," and unlike "lightly obscured," this bonus isn't specified to only affect perception checks involving sight. Full cover grants no stealth bonus, curiously. Note that many other references to cover in the rules only reference the usual +2 to AC and Dexterity saves, though, so it's possible this is a typo.
But if you take this RAW, you can't have glass or other transparent objects grant defensive cover without also granting stealth bonuses.
In addition, combined with the "Stealth and Hinding" text on pg. 411, I'm not sure the unmodified stealth check even exists any more: you must be "behind something (cover), obscured, invisible, or otherwise out of sight" to attempt to hide. With obscured and invisibility granting advantage, and cover granting +2/+5, I can't figure out a stealth situation in which you'd roll without at least one of these modifiers. And since the rules specificalyl specify that once you make a stealth roll, it "is used until you stop hiding" it's not like you'd start hiding in cover, move out of cover, and ever need to roll stealth again.
Seems like another place to ask for clarification...?