I have not read where any of the real QB's have been getting any training, but IMO, JM is the one that really needs help.
To BamaMoons point, it's such a normal thing that QBs (and other HS/college athletes across sports really) get individual training in the off-season that it's not really newsworthy. Seriously - a vast, vast majority of them go get position specific work. I've no clue why it seems to be so newsworthy that JM is doing it. It would be way more of an outlier if he wasn't doing it. It's almost like there is a portion of the media trying to back up their own narrative around him - 'See! Look how hard he's working!', etc... I'm not going to spend the time to try to find it, but I read an article before or during the '22 season that mentioned JMs QB coach that he'd been working with for quite a while - multiple years going back into HS I believe. It not really new that he's getting a QB specific coaching, other than it seems he's changed coaches so perhaps that is a good thing.
Last years article about TS was already posted. I saw an article with a lot of videos about Mack getting coaching somewhere out west over spring break as well. I'm sure Lonergan is also.
It's
NORMAL for advanced athletes to do this.
Case in point:
My son hasn't turned 14, yet last summer in addition to his club team practices (2x-3x a week) and HS strength workouts (2x a week), he was doing a day a week with a position coach (sometimes two if it was a non-tournament week) and would try to fit in an additional speed/agility day. That continued through the fall offseason (in additional to "optional, captains" practices for HS, and weekly club practices) until they got to winter tournament season and spring varsity. Then he'll go into the backyard a couple times a week to just shoot and get throw/catch practice on his own when he needs a brain break from school.
It's a lot, but not unusual at all. Many are doing that or more. A friend on his club team was doing 3 days a week of individual positional work every week, even if he had club or school practices that day as well.
Just this weekend, our HS QB had a private trainer/coach on the turf with him working on mechanics and had a handful of WRs out there getting route work in to maximize the throws he could get in a short period of time. The QB is a junior now.
Again - it's totally normal for athletes at HS and college now to work with coaches outside their program to improve across the entire year, especially outside the standard practice timeframes that are allowed in HS and college.