Re: Little things that bug you/me about the forum
⭐ Merited by joker_josue (1)
What do you think about just setting the height as default?
Wasn't that basically what I ended up suggesting when we last spoke about this? 
It makes me think that maybe a sane default choice for TalkImg would be BBCode that includes just the height attribute...
And then later:
Ha! Reading my own thoughts, I see that I've left you with three options:
(1) Do nothing, and rely on this problem being fixed in another way.
(2) Make the default TalkImg BBCode include both a width and a height attribute.
(3) Make the default TalkImg BBCode include just the height attribute.
I think if it were up to me, the choice would be between 1 and 3. (But, remember, I only have a hunch that for typical forum content vertical layout shifts can mostly be avoided if the browser knows just the height of an image before loading it. So, you should probably do nothing until someone tests that hypothesis. If it turns out that browsers really are super picky about needing both dimensions before they can do anything clever around avoiding layout shifts, then the choice is between 1 and 2, and in that case, the tradeoffs aren't so clear, and with unclear tradeoffs, I tend toward inaction.)
(1) Do nothing, and rely on this problem being fixed in another way.
(2) Make the default TalkImg BBCode include both a width and a height attribute.
(3) Make the default TalkImg BBCode include just the height attribute.
I think if it were up to me, the choice would be between 1 and 3. (But, remember, I only have a hunch that for typical forum content vertical layout shifts can mostly be avoided if the browser knows just the height of an image before loading it. So, you should probably do nothing until someone tests that hypothesis. If it turns out that browsers really are super picky about needing both dimensions before they can do anything clever around avoiding layout shifts, then the choice is between 1 and 2, and in that case, the tradeoffs aren't so clear, and with unclear tradeoffs, I tend toward inaction.)
I remember wondering at the time: "Why did he go for the option that I least recommended?"
The thing is, back then, we (you, me, and Loyce, I mean) were only really considering things in terms of hoping to reduce the probability of layout shifts by accepting a possible increase in the amount of users incorrectly adjusting [img] dimensions, but, the issue that Loyce just now reported is actually orthogonal to all of that, and would've presented even if you had gone with option 3 (at least, according to the quick test that I just did).
So, that kind of leaves you in a tricky spot, where the only thing that you can really do from TalkImg's end (to both reduce the problem of people making incorrect BBCode size adjustments, and the problem where an image with a height attribute will sometimes not have its aspect ratio maintained during responsive down-sizing) is to revert the change and go with option 1 (which puts you back where you started in terms of the layout shift problem).
