Currently there seem to be 2 different starting biomes, the 'old' one and the new Forest/Arbour biome. The old biome had a lot of 'buried objects', which would contain Muckroot, Mealwood seeds, or rarely Hatches/Blossom seeds/Briar Seeds. The new one only has a few Mirth Leaf seeds. The reason this is an issue is that if you play on maximum food difficulty, you are often reliant on digging up early food while you amass enough seeds for a sufficiently sized Mealwood Farm/Blossom farm. But this new biome has no food to dig. To add insult to injury, the lack of diggable Mealwood seeds also slows down the rate you can expand your Mealwood farm, making you have to rely on other food sources for longer (and there are no Blossoms at all). And this new biome also seems to have little starting water, so even relying on Mush Bars to bridge the gap isn't really a viable strategy. On normal difficulty you can survive off the starting Mealwood and set up a farm fast enough, but on maximum difficulty you are practically forced to let some dupes starve regardless of your strategy.
While most of the other aspects of the new start biome seem relatively balanced (you have to use alternative methods), this seems pretty uneven as there isn't really an alternative method given. And it doesn't seem like the new start biome is intended to be significantly harder on maximum difficulty then the old one, since the old starter biome is present on many of the 'hard' maps.
Plus, even ignoring balance considerations, it seems odd that there are many times less diggable objects to find in the new biome then the old one. Adding in some (rare) buried Oxyfern/Arbour Tree seeds would make sense, along with Mealwood Seeds and some kind of basic food item like Muckroot to even out the early game food situation and give the player things to find of roughly even value to the other start biome.
Edit: Well not long after post, buried Mealwood seeds were added to the biome. Would still like to see more variety in buried objects, but it's a significant improvement and at least smooths things out significantly.
Start a game on a map that has the new Arbour/Forest starting biome, if you dig the entire biome out the only thing you will find buried are a few Mirth Leaf seeds, no other seeds, food items or anything, which is very different from the other possible starter biome.