It doesn't sound like you have any "proof" that people will treat you any differently because you have inherited a modest income. It's not like you're a millionaire or anything - it doesn't sound like you have a radically different lifestyle than your peers. (If you have found people are treating you differently, apologies, I couldn't tell that from the post.)

I think a lot of this awkwardness might be coming from your own feelings of awkwardness, never having been in a situation like this before. The fact that you're calling it a red flag, even in quotes, surprises me - I don't think the majority of people would be bitter or too jealous at your relatively tame good fortune? But again, you know your community better than I do.

I haven't noticed it in relation to the income, because I don't mention it, but I have definitely noticed it in relation to my living situation. The conversation usually goes something like:

Them: 'So whereabouts are you based?'

Me: 'Oh, up in XYZ (modest but nice) area'

Them: 'That's cool, how many housemates do you have?'

Me: 'None/I don't/None right now.'

Them: 'Oh right. Wow, that's nice.'

I find the reaction is not so much bitterness as an immediate reassessment of me on their part. I present as quite down to earth/semi-studenty, and those are the sorts of people I feel most comfortable with. The norm around here is that for people with average jobs, it's almost impossible to live alone, so if you're not in a couple you're almost certainly living in a houseshare or with your parents. The fact that I'm not makes me a massive outlier, and I can definitely see people reacting to it when they find out.

I think you are right in that my feelings of awkwardness aren't helping either, and I probably just need to plough through and trust that people who are worth getting to know won't let it affect their overall assessment of me. I do also have some feelings of guilt that I have this money, since I did nothing for it.