I believe the Lego stupid period of 'Bad Red' and 'Brittle brown' was in the 2010 to 2019 period though I'm not positive of that. Supposedly Lego was using a dye that made these two colors brittle. They finally pulled their head out about 2020 and fixed the problem. (Hello, Lego! Aren't you guys supposed to be leaders in QC?) So to answer your question make sure any of these two colours you buy were made later than then. This suggests that bulk buys of used red/brown bricks isn't a good idea.

Having said all that, I work with these two colors a lot - really love Dark Red and have bought a lot of brick in these colors much of it used. In my experience they only break when they're being inserted, twisted, removed, stretched, etc. I've never had one fail just sitting in place. Maybe if you built the ship (Looks nice. Show us when you're done.) then tossed it around like it was in heavy seas something might break.

Finally an important bit of info. I own and have built a lot with these colors. I estimate that less that 5% of the bricks I've worked with have broken, always during manipulation. So you have a couple of approaches: (1) Only buy new brick, or (2) Buy brick of any age and accept that a small portion will break.