It is stated in human interface guidelines and material design that the touch target should be 44x44 & 48x48 respectively. Many top apps don't follow; isn't this an accessibility issue?
There are two ways to look at accessibility issues:
- Legal compliance
For legal compliance, most countries use WCAG level AA as their guideline. The latest version of WCAG is 2.1 but some countries still use the older 2.0 (which is over 14 years old). Version 2.2 might come out this year (2023).
In version 2.0, there was nothing about target sizes.
In version 2.1, a new AAA guideline was added that required a 44x44 target size. However, since it's a AAA guideline and most countries only require AA conformance, there isn't a legal requirement to adhere to it.
In version 2.2 (possibly coming in 2023), there is a new AA guideline requiring at least a 24x24 target size. Since it's a AA guideline, when countries adopt the new version, there will be a requirement to conform to the target size. Notice, though, that it's 24x24 and not 44x44. My guess is that since a minimum target size will be required in version 2.2, the guidelines are easing into it and not requiring 44x44 immediately.
Now, does that mean you shouldn't try to have a 44x44 target size now instead of waiting until it's legally required? That's where the second way to view accessibility issues comes into play - usability. Even if you are not required to have a certain target size, it's always good to implement features that are good for the user, whether required or not.
So to answer your original question on whether target sizes smaller than 44x44 are an accessibility issue, the answer is no from a legal compliance perspective but perhaps yes from a usability perspective.