Yes, this is a great example of what I mean in the footnote that I stuck at the end of that section -- people often think that the problem is triggered by too much or not enough whitespace, because that's the obvious difference that is the easiest to visually identify when comparing two designs where one causes problems for them and one doesn't, but what little we know about the science says it's actually not whitespace at all, it's the proportion of text size to text-block width. You can have two text blocks on the exact same screen with the exact same margins, padding, line-height, and whitespace, and the one with the smaller font is more likely to trigger photosensitive issues in people, because the ratio of letter size to line width will be greater, and it's the ratio that causes the problem.
No one has been able to quantify the exact ratios that cause problems and the ones that don't. To make it worse, it's not a bell curve, and it's not that there's a specific window that's "okay" and anything outside that window is likely to be a problem: as you go through changing the ratios, it's more like "okay, okay, okay, small problem, okay, small problem, okay, BIG PROBLEM, okay, small problem", etc. And if that wasn't enough of a problem, other visual elements on the screen can affect what ratios people have problems with and which ones they don't, because best evidence points to it being a cumulative thing.
Something like color contrast affecting readability is very well-studied by now: we know what contrast level hits the sweet spot of "enough contrast not to cause readability issues, not so much contrast it causes eye strain", and there are tools that can do it automatically for you. Letter-size-to-display-width ratio is a thing where the best anyone can do is "accessibility experts know that getting it wrong causes people problems, but there is no objective way for anyone to quantify if you have gotten it right". All the accessibility guidelines and best practices about element width stem from other core issues, like dyslexia.
There's a bunch of us who are the early-stage test pool for "have we gotten it right" because we do get problems when it's wrong, myself included (although size-to-width ratio isn't my primary photosensitivity trigger), and then we have a bunch of folks who have photosensitivity problems who make it a point to enable every beta we ask people to enable so they can give us a wider range of feedback, but unfortunately there's never any way to tell whether your "this is probably not going to cause issues" prediction has hit 90% confidence, 95% confidence, or 99% confidence.
Anyway, tl;dr: if you're having problems on small screens, the other cumulative tweaks may fix it, but my probably-counterintuitive prediction of what will likely have the best chance at working for you: bump your font size up 2 points larger.
no subject
No one has been able to quantify the exact ratios that cause problems and the ones that don't. To make it worse, it's not a bell curve, and it's not that there's a specific window that's "okay" and anything outside that window is likely to be a problem: as you go through changing the ratios, it's more like "okay, okay, okay, small problem, okay, small problem, okay, BIG PROBLEM, okay, small problem", etc. And if that wasn't enough of a problem, other visual elements on the screen can affect what ratios people have problems with and which ones they don't, because best evidence points to it being a cumulative thing.
Something like color contrast affecting readability is very well-studied by now: we know what contrast level hits the sweet spot of "enough contrast not to cause readability issues, not so much contrast it causes eye strain", and there are tools that can do it automatically for you. Letter-size-to-display-width ratio is a thing where the best anyone can do is "accessibility experts know that getting it wrong causes people problems, but there is no objective way for anyone to quantify if you have gotten it right". All the accessibility guidelines and best practices about element width stem from other core issues, like dyslexia.
There's a bunch of us who are the early-stage test pool for "have we gotten it right" because we do get problems when it's wrong, myself included (although size-to-width ratio isn't my primary photosensitivity trigger), and then we have a bunch of folks who have photosensitivity problems who make it a point to enable every beta we ask people to enable so they can give us a wider range of feedback, but unfortunately there's never any way to tell whether your "this is probably not going to cause issues" prediction has hit 90% confidence, 95% confidence, or 99% confidence.
Anyway, tl;dr: if you're having problems on small screens, the other cumulative tweaks may fix it, but my probably-counterintuitive prediction of what will likely have the best chance at working for you: bump your font size up 2 points larger.