I’m starting to think there might be a market for Ziplock bag holders that allow you to ladle in the soupy goodness with ease.
Somebody invent this so I can give you all my money! 
I wash and reuse mine. Some of my bags have gone through several seasons, and once the seals become a bit too suspect for food use they mostly find service in the greenhouse or garage, or for my hobby of making dresses for Lady Gaga.
I rinse and reuse mine, often for non-food use. When traveling I need ziplocks for toiletries, for example.
It does not seem likely that leeches would get anywhere near your food while it’s in a freezer, and in addition mason jars should also be safe from chemicals leaching into your food. The same applies to the Ziploc bag option.
That’s what I was going to say as well- you can freeze them flat, and stack them horizontally or vertically in the freezer much more efficiently than containers. Plus, without much air space, there’s little freezer burn. And since their surface area to volume ratio is fairly high, they defrost pretty quickly as well.
I’d be much more concerned about throwing out some perfectly good chili due to a broken Mason jar. Modern containers that are MEANT to contain food aren’t going to leech chemicals into it. As for the staining, I use the stained ones strictly for tomato based products like chili, spagetti sauce, soup, stew, etc. And they’re reusable, not permanent fixtures. At some point of freezing, reheating, etc. those containers develop weak spots and it’s time to demote them to holding crap in the garage or gardening shed.
Ball makes a line of freezer jars if you’re interested. Of course, they’re plastic.
My grandmother used to use wax milk cartons. She’d cut the top off and then cut down about 2 inches on each corner creating flaps. She’d fill the carton within 1/2" of where the cuts stopped and fold the flaps over. Then she’d tape it up with masking tape. they made nice little cubes that stacked well. I don’t think it would be considered wise or efficient given the recent gains in plastic containers, but it’s an alternative.
I hadn’t considered zip lock bags. That’s an interesting option.
I just wanted something easy to fill, store and wash afterwards. Jars seemed ideal. But they do take up more room than flattened bags.
I see they have a hanging rack for bags.
https://www.amazon.com/gp/aw/d/B07JB2HYFK/ref=sspa_mw_detail_1?ie=UTF8&psc=1
Ziploc makes flat bottomed bags that stand up while you fill them. I don’t like them because they don’t lay as flat. For filling regular bags I have a particular green Tupperware bowl I sit the bags down in and it holds it up til I put my food in. Squeeze out the air and zip. Easy peasy. Oh, and I do reuse my bags. I am kinda anal about it, really. Drives my family crazy.
I can remember waxed cardboard boxes for home freezing, mom used them back in the early 70s - just like the little BirdsEye veggie boxes. I could get behind a revival of these, they would degrade nicely in a landfill, or be fine for burning to start a fire in the woodstove.
They actually work surprisingly well, as they’re engineered such that they don’t actually have to hold up the weight of the bag and what’s filling it, but just the sides of the bag itself.
I almost missed this. Thanks Zipper!
When I was but a sprog my mother put up gallons of soup in repurposed plastic ice cream containers. Our favorite brand came in heavy gallon sizes, and the lids snapped on with authority. Our freezer was always full of “Grandma’s Summer Soup” or “Grandma’s Winter Soup” (the only difference being the specific vegetables and the addition of fresh or creamed corn.)
I’m not trying to be a jerk or thread shit but given the amount of salt water you apparently ingest, leeching chemicals should be the least of your health concerns.
As to the OP, I agree with the masses - go baggies.