Work allocation changed since diclosure to supervisor

My manager has always known I'm autistic. She works on another site and generally is only on my site once per week, less now due to covid.

My supervisor and I don't get on, manager disclosed to her that I'm autistic because she said that it would help our working relationship. Frankly I think the woman is just a bully and nothing would help but manager really pressed the issue and I eventually relented.

I've noticed that since the disclosure I've been allocated all the boring, easy tasks. I'm a higher level healthcare assistant and my job contract involves needing to learn lots of specific skills. I was on a higher pay grade to the other healthcare assistants but their union argued that they'd been getting under paid. Lots of the healthcare assistants across the whole health board got regraded but on the job they were doing, they don't need to learn any extra skills even though we are all being paid the same. 

Some of the HCAs have chosen to learn some of my skills as their job is really boring and my job is more interesting but some decided they didn't want to. These people are now being given my jobs to do and my whole schedule next week is me doing what used to be their job. Thinking about it this has gone on since I was outed to the supervisor (who makes our schedule).

I want to speak to my manager about it but is it being petty?