That is a nice piece of bread .. and nice bourgignon .... congrats ....
I guess some possible answers to your question was that the oven wasn't hot enough or you didn't bake it long enough. Another possibility was too much steam that wasn't allowed to escape early enough. The steam is only to improve crust which takes a short time. Another possibility is that you may have accidently added some olive oil?

I steam for 5 minutes release heat with door open for least amount of time and whack up the heat. So steam injection followed by harsh dry heat.
One idea, you will improve the texture a bit if you make some cuts in the surface. For your first few loaves (I'd concentrate on getting one thing right at a time ....) don't use a knife or blade but a pair of scissors and cut into the surface. A series of cuts. This allows the bread to "open" more. Cutting with a blade or knife is a bit of a knack and often the bread collapses or misshapes as one learns - so scissors.
It's all about the taste and a home made rustic appearance experience and it sounds like you scored a hit.
In time substitute some of the final flour so you end up with around 180gm white, 35gm wholemeal and 35gm rye flour and perhaps a squirt of runny honey. I also like adding a few onion (Nigella) seeds. So that means that only 20% of the total flour isn't white ie 70gms out of a total of 350 and replace a few ml of water with the honey ..... eg
That shiney surface comes about as a result of a longer first mix and that steam injection, and for me both the crust, texture and taste is exactly to my personal taste as a "daily bread"..
These small adjustments and changes complements the poolish approach and gives a lot of character and flavour. Once you've made these small changes you'll find yourself thinking about bread a lot of the day ....
Completed weight 600
Hydration 70%
Dry 353
Liquid 247
Dry 100.00%
Italian Flour 0.00%
Canadian Flour 176 50.00%
Wholemeal Flour 35 10.00%
Rye Flour 36 10.20%
Poolish Flour 99 28.00%
Salt 6 1.80%
Yeast 0.00%
Vital Wheat 0.00%
353
Wet 100.00%
Water 141 57.00%
Poolish Water 101 41.00%
Milk 0.00%
Oil 0.00%
Honey 5 2.00%
247
... and some different "daily breads" .... including one similar to yours and another with caraway and the other with a higher amount of wholemeal.
Can you now see why that as a reasonable compromise going the poolish route in favour of sour starter gives a lot of the flavour benefit with no downside? You can almost as an adjunct to your last visit to the kitchen each night, take 30 seconds and make a small poolish even if your plans to make bread the following day aren't firm. It is quick easy and requires no skill or concentration. The following morning you just add the other stuff and put it under the mixer. I much prefer the flavour from poolish starter than sourdough in fact. It's more subtle. In time the flavour will improve from where you are. And how useful it is to keep your own running spreadsheet like the one above to record your adjustments and learn from your own experiments and experience rather than using recipes? In this way understanding and feeling the principles by self-learning you build your own perfect loaf rather than someone else's.
And don't start me off about home made bagels ....
Well done.