I'm pretty sure what you're describing is this long-standing bug[1] I've experienced only when using Mobile Safari on Reddit - affecting both old.reddit.com and the (horrible) modern Reddit. It just doesn't happen in other browsers/engines except on iOS. It's especially annoying on an iPad when I tend to use back/forward instead of open-in-new-tab-then-close on iPhone.
[1] At least, I hope it's a bug.
For mobile Safari on iOS/iPad, the back button imo is just completely broken. It’s either a bug, or Apple might say I’m ‘holding it wrong’. One version it just stopped doing its one job correctly and it’s messing with my mental model of how I arrived at each tab. Currently:
Safari iOS: Be on a page, tap hold a link, click Open in new tab, go to new tab. The Back button should be grayed out and isn’t, and clicking it closes the tab. (???)
Chrome iOS: Be on a page, tap hold a link, click Open in new tab, go to new tab. Back button correctly grayed out as the tab has nowhere to go back to.
A bug that just coincidentally affects the only reddit visitors that are worth any money?