I think the impact on hearing impaired students is treated as a niche issue which can be resolved with clear masks etc. but it's really not.
Around 2% of children have diagnosable hearing impairment. But there is a spectrum of hearing loss and many children will have below average hearing which isn't at the level of being diagnosable or hasn't yet been diagnosed (given that hearing isn't routinely tested). I am in this category and struggle to hear people with masks. It's partly about the inability to see someone's face but also the muffling. Looser thinner masks make it easier to hear someone but are also essentially pointless.
A lot of people with normal hearing seem to struggle to hear people speaking with a mask on, even in one to one interactions where they are close to someone. I'm frequently misheard by staff in shops etc. while wearing a mask.
In an environment where a main purpose of being there is to hear someone speak and where following the complexities of what they are saying is important, masks are going to be highly detrimental for many students.
Teachers may not necessarily realise. I would have sat quietly in a class with a mask on if I had been a student now but wouldn't have heard half of what was being said.
And there is very limited reason to think that cloth masks are going to significantly reduce staff or student absence due to covid. There does not appear to have been a reduction in cases in Scotland compared to England despite the difference in mask rules. The best studies on this suggest that cloth masks are around 7% effective (and those studies have been criticised for the way they analysed the data anyway). We know that omicron is more infectious so shouldn't expect masks to work as well, particularly over a long time period. We know that many classrooms are not well ventilated. So you have pupils sitting next to each other for around 6 hours breathing in the same air. It seems unlikely that masks would be the difference between catching omicron or not in those circumstances.
I just can't see that the cost benefit is there. It seems to be about being seen to do something and, in some quarters, a belief that because there is no downside to masks, we might as well try them in case they work a bit. There's an emotive argument about "protecting" children and teachers but that isn't the intention of the policy anymore because it is accepted that people will eventually be exposed to covid in any case - no one expects wearing a mask to prevent eventual infection just possibly to slow it down a bit.